Programs & Examples On #Innodb

InnoDB is an ACID-compliant transactional storage engine for MySQL that uses MultiVersion Concurrency Control (MVCC).

How to regex in a MySQL query

In my case (Oracle), it's WHERE REGEXP_LIKE(column, 'regex.*'). See here:

SQL Function

Description


REGEXP_LIKE

This function searches a character column for a pattern. Use this function in the WHERE clause of a query to return rows matching the regular expression you specify.

...

REGEXP_REPLACE

This function searches for a pattern in a character column and replaces each occurrence of that pattern with the pattern you specify.

...

REGEXP_INSTR

This function searches a string for a given occurrence of a regular expression pattern. You specify which occurrence you want to find and the start position to search from. This function returns an integer indicating the position in the string where the match is found.

...

REGEXP_SUBSTR

This function returns the actual substring matching the regular expression pattern you specify.

(Of course, REGEXP_LIKE only matches queries containing the search string, so if you want a complete match, you'll have to use '^$' for a beginning (^) and end ($) match, e.g.: '^regex.*$'.)

How to shrink/purge ibdata1 file in MySQL

That ibdata1 isn't shrinking is a particularly annoying feature of MySQL. The ibdata1 file can't actually be shrunk unless you delete all databases, remove the files and reload a dump.

But you can configure MySQL so that each table, including its indexes, is stored as a separate file. In that way ibdata1 will not grow as large. According to Bill Karwin's comment this is enabled by default as of version 5.6.6 of MySQL.

It was a while ago I did this. However, to setup your server to use separate files for each table you need to change my.cnf in order to enable this:

[mysqld]
innodb_file_per_table=1

https://dev.mysql.com/doc/refman/5.6/en/innodb-file-per-table-tablespaces.html

As you want to reclaim the space from ibdata1 you actually have to delete the file:

  1. Do a mysqldump of all databases, procedures, triggers etc except the mysql and performance_schema databases
  2. Drop all databases except the above 2 databases
  3. Stop mysql
  4. Delete ibdata1 and ib_log files
  5. Start mysql
  6. Restore from dump

When you start MySQL in step 5 the ibdata1 and ib_log files will be recreated.

Now you're fit to go. When you create a new database for analysis, the tables will be located in separate ibd* files, not in ibdata1. As you usually drop the database soon after, the ibd* files will be deleted.

http://dev.mysql.com/doc/refman/5.1/en/drop-database.html

You have probably seen this:
http://bugs.mysql.com/bug.php?id=1341

By using the command ALTER TABLE <tablename> ENGINE=innodb or OPTIMIZE TABLE <tablename> one can extract data and index pages from ibdata1 to separate files. However, ibdata1 will not shrink unless you do the steps above.

Regarding the information_schema, that is not necessary nor possible to drop. It is in fact just a bunch of read-only views, not tables. And there are no files associated with the them, not even a database directory. The informations_schema is using the memory db-engine and is dropped and regenerated upon stop/restart of mysqld. See https://dev.mysql.com/doc/refman/5.7/en/information-schema.html.

TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT maximum storage sizes

From the documentation (MySQL 8) :

      Type | Maximum length
-----------+-------------------------------------
  TINYTEXT |           255 (2 8−1) bytes
      TEXT |        65,535 (216−1) bytes = 64 KiB
MEDIUMTEXT |    16,777,215 (224−1) bytes = 16 MiB
  LONGTEXT | 4,294,967,295 (232−1) bytes =  4 GiB

Note that the number of characters that can be stored in your column will depend on the character encoding.

How do I see all foreign keys to a table or column?

If you use InnoDB and defined FK's you could query the information_schema database e.g.:

SELECT * FROM information_schema.TABLE_CONSTRAINTS 
WHERE information_schema.TABLE_CONSTRAINTS.CONSTRAINT_TYPE = 'FOREIGN KEY' 
AND information_schema.TABLE_CONSTRAINTS.TABLE_SCHEMA = 'myschema'
AND information_schema.TABLE_CONSTRAINTS.TABLE_NAME = 'mytable';

Why is MySQL InnoDB insert so slow?

things that speed up the inserts:

  • i had removed all keys from a table before large insert into empty table
  • then found i had a problem that the index did not fit in memory.
  • also found i had sync_binlog=0 (should be 1) even if binlog is not used.
  • also found i did not set innodb_buffer_pool_instances

How can I rebuild indexes and update stats in MySQL innoDB?

Why? One almost never needs to update the statistics. Rebuilding an index is even more rarely needed.

OPTIMIZE TABLE tbl; will rebuild the indexes and do ANALYZE; it takes time.

ANALYZE TABLE tbl; is fast for InnoDB to rebuild the stats. With 5.6.6 it is even less needed.

How do I repair an InnoDB table?

The following solution was inspired by Sandro's tip above.

Warning: while it worked for me, but I cannot tell if it will work for you.

My problem was the following: reading some specific rows from a table (let's call this table broken) would crash MySQL. Even SELECT COUNT(*) FROM broken would kill it. I hope you have a PRIMARY KEY on this table (in the following sample, it's id).

  1. Make sure you have a backup or snapshot of the broken MySQL server (just in case you want to go back to step 1 and try something else!)
  2. CREATE TABLE broken_repair LIKE broken;
  3. INSERT broken_repair SELECT * FROM broken WHERE id NOT IN (SELECT id FROM broken_repair) LIMIT 1;
  4. Repeat step 3 until it crashes the DB (you can use LIMIT 100000 and then use lower values, until using LIMIT 1 crashes the DB).
  5. See if you have everything (you can compare SELECT MAX(id) FROM broken with the number of rows in broken_repair).
  6. At this point, I apparently had all my rows (except those which were probably savagely truncated by InnoDB). If you miss some rows, you could try adding an OFFSET to the LIMIT.

Good luck!

MySQL DROP all tables, ignoring foreign keys

DB="your database name" \
    && mysql $DB < "SET FOREIGN_KEY_CHECKS=0" \
    && mysqldump --add-drop-table --no-data $DB | grep 'DROP TABLE' | grep -Ev "^$" | mysql $DB \
    && mysql $DB < "SET FOREIGN_KEY_CHECKS=1"

What's the difference between MyISAM and InnoDB?

The main differences between InnoDB and MyISAM ("with respect to designing a table or database" you asked about) are support for "referential integrity" and "transactions".

If you need the database to enforce foreign key constraints, or you need the database to support transactions (i.e. changes made by two or more DML operations handled as single unit of work, with all of the changes either applied, or all the changes reverted) then you would choose the InnoDB engine, since these features are absent from the MyISAM engine.

Those are the two biggest differences. Another big difference is concurrency. With MyISAM, a DML statement will obtain an exclusive lock on the table, and while that lock is held, no other session can perform a SELECT or a DML operation on the table.

Those two specific engines you asked about (InnoDB and MyISAM) have different design goals. MySQL also has other storage engines, with their own design goals.

So, in choosing between InnoDB and MyISAM, the first step is in determining if you need the features provided by InnoDB. If not, then MyISAM is up for consideration.

A more detailed discussion of differences is rather impractical (in this forum) absent a more detailed discussion of the problem space... how the application will use the database, how many tables, size of the tables, the transaction load, volumes of select, insert, updates, concurrency requirements, replication features, etc.


The logical design of the database should be centered around data analysis and user requirements; the choice to use a relational database would come later, and even later would the choice of MySQL as a relational database management system, and then the selection of a storage engine for each table.

1114 (HY000): The table is full

EDIT: First check, if you did not run out of disk-space, before resolving to the configuration-related resolution.

You seem to have a too low maximum size for your innodb_data_file_path in your my.cnf, In this example

innodb_data_file_path = ibdata1:10M:autoextend:max:512M

you cannot host more than 512MB of data in all innodb tables combined.

Maybe you should switch to an innodb-per-table scheme using innodb_file_per_table.

How to change value for innodb_buffer_pool_size in MySQL on Mac OS?

For standard OS X installations of MySQL you will find my.cnf located in the /etc/ folder.

Steps to update this variable:

  1. Load Terminal.
  2. Type cd /etc/.
  3. sudo vi my.cnf.
  4. This file should already exist (if not please use sudo find / -name 'my.cnf' 2>1 - this will hide the errors and only report the successfile file location).
  5. Using vi(m) find the line innodb_buffer_pool_size, press i to start making changes.
  6. When finished, press esc, shift+colon and type wq.
  7. Profit (done).

How do I quickly rename a MySQL database (change schema name)?

Well there are 2 methods:

Method 1: A well-known method for renaming database schema is by dumping the schema using Mysqldump and restoring it in another schema, and then dropping the old schema (if needed).

From Shell

 mysqldump emp > emp.out
 mysql -e "CREATE DATABASE employees;"
 mysql employees < emp.out 
 mysql -e "DROP DATABASE emp;"

Although the above method is easy, it is time and space consuming. What if the schema is more than a 100GB? There are methods where you can pipe the above commands together to save on space, however it will not save time.

To remedy such situations, there is another quick method to rename schemas, however, some care must be taken while doing it.

Method 2: MySQL has a very good feature for renaming tables that even works across different schemas. This rename operation is atomic and no one else can access the table while its being renamed. This takes a short time to complete since changing a table’s name or its schema is only a metadata change. Here is procedural approach at doing the rename:

Create the new database schema with the desired name. Rename the tables from old schema to new schema, using MySQL’s “RENAME TABLE” command. Drop the old database schema. If there are views, triggers, functions, stored procedures in the schema, those will need to be recreated too. MySQL’s “RENAME TABLE” fails if there are triggers exists on the tables. To remedy this we can do the following things :

1) Dump the triggers, events and stored routines in a separate file. This done using -E, -R flags (in addition to -t -d which dumps the triggers) to the mysqldump command. Once triggers are dumped, we will need to drop them from the schema, for RENAME TABLE command to work.

 $ mysqldump <old_schema_name> -d -t -R -E > stored_routines_triggers_events.out

2) Generate a list of only “BASE” tables. These can be found using a query on information_schema.TABLES table.

 mysql> select TABLE_NAME from information_schema.tables where 
    table_schema='<old_schema_name>' and TABLE_TYPE='BASE TABLE';

3) Dump the views in an out file. Views can be found using a query on the same information_schema.TABLES table.

mysql> select TABLE_NAME from information_schema.tables where 
   table_schema='<old_schema_name>' and TABLE_TYPE='VIEW';
 $ mysqldump <database> <view1> <view2> … > views.out

4) Drop the triggers on the current tables in the old_schema.

mysql> DROP TRIGGER <trigger_name>;
...

5) Restore the above dump files once all the “Base” tables found in step #2 are renamed.

mysql> RENAME TABLE <old_schema>.table_name TO <new_schema>.table_name;
...
$ mysql <new_schema> < views.out
$ mysql <new_schema> < stored_routines_triggers_events.out

Intricacies with above methods : We may need to update the GRANTS for users such that they match the correct schema_name. These could fixed with a simple UPDATE on mysql.columns_priv, mysql.procs_priv, mysql.tables_priv, mysql.db tables updating the old_schema name to new_schema and calling “Flush privileges;”. Although “method 2" seems a bit more complicated than the “method 1", this is totally scriptable. A simple bash script to carry out the above steps in proper sequence, can help you save space and time while renaming database schemas next time.

The Percona Remote DBA team have written a script called “rename_db” that works in the following way :

[root@dba~]# /tmp/rename_db
rename_db <server> <database> <new_database>

To demonstrate the use of this script, used a sample schema “emp”, created test triggers, stored routines on that schema. Will try to rename the database schema using the script, which takes some seconds to complete as opposed to time consuming dump/restore method.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| emp                |
| mysql              |
| performance_schema |
| test               |
+--------------------+


[root@dba ~]# time /tmp/rename_db localhost emp emp_test
create database emp_test DEFAULT CHARACTER SET latin1
drop trigger salary_trigger
rename table emp.__emp_new to emp_test.__emp_new
rename table emp._emp_new to emp_test._emp_new
rename table emp.departments to emp_test.departments
rename table emp.dept to emp_test.dept
rename table emp.dept_emp to emp_test.dept_emp
rename table emp.dept_manager to emp_test.dept_manager
rename table emp.emp to emp_test.emp
rename table emp.employees to emp_test.employees
rename table emp.salaries_temp to emp_test.salaries_temp
rename table emp.titles to emp_test.titles
loading views
loading triggers, routines and events
Dropping database emp

real    0m0.643s
user    0m0.053s
sys     0m0.131s


mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| emp_test           |
| mysql              |
| performance_schema |
| test               |
+--------------------+

As you can see in the above output the database schema “emp” was renamed to “emp_test” in less than a second. Lastly, This is the script from Percona that is used above for “method 2".

#!/bin/bash
# Copyright 2013 Percona LLC and/or its affiliates
set -e
if [ -z "$3" ]; then
    echo "rename_db <server> <database> <new_database>"
    exit 1
fi
db_exists=`mysql -h $1 -e "show databases like '$3'" -sss`
if [ -n "$db_exists" ]; then
    echo "ERROR: New database already exists $3"
    exit 1
fi
TIMESTAMP=`date +%s`
character_set=`mysql -h $1 -e "show create database $2\G" -sss | grep ^Create | awk -F'CHARACTER SET ' '{print $2}' | awk '{print $1}'`
TABLES=`mysql -h $1 -e "select TABLE_NAME from information_schema.tables where table_schema='$2' and TABLE_TYPE='BASE TABLE'" -sss`
STATUS=$?
if [ "$STATUS" != 0 ] || [ -z "$TABLES" ]; then
    echo "Error retrieving tables from $2"
    exit 1
fi
echo "create database $3 DEFAULT CHARACTER SET $character_set"
mysql -h $1 -e "create database $3 DEFAULT CHARACTER SET $character_set"
TRIGGERS=`mysql -h $1 $2 -e "show triggers\G" | grep Trigger: | awk '{print $2}'`
VIEWS=`mysql -h $1 -e "select TABLE_NAME from information_schema.tables where table_schema='$2' and TABLE_TYPE='VIEW'" -sss`
if [ -n "$VIEWS" ]; then
    mysqldump -h $1 $2 $VIEWS > /tmp/${2}_views${TIMESTAMP}.dump
fi
mysqldump -h $1 $2 -d -t -R -E > /tmp/${2}_triggers${TIMESTAMP}.dump
for TRIGGER in $TRIGGERS; do
    echo "drop trigger $TRIGGER"
    mysql -h $1 $2 -e "drop trigger $TRIGGER"
done
for TABLE in $TABLES; do
    echo "rename table $2.$TABLE to $3.$TABLE"
    mysql -h $1 $2 -e "SET FOREIGN_KEY_CHECKS=0; rename table $2.$TABLE to $3.$TABLE"
done
if [ -n "$VIEWS" ]; then
    echo "loading views"
    mysql -h $1 $3 < /tmp/${2}_views${TIMESTAMP}.dump
fi
echo "loading triggers, routines and events"
mysql -h $1 $3 < /tmp/${2}_triggers${TIMESTAMP}.dump
TABLES=`mysql -h $1 -e "select TABLE_NAME from information_schema.tables where table_schema='$2' and TABLE_TYPE='BASE TABLE'" -sss`
if [ -z "$TABLES" ]; then
    echo "Dropping database $2"
    mysql -h $1 $2 -e "drop database $2"
fi
if [ `mysql -h $1 -e "select count(*) from mysql.columns_priv where db='$2'" -sss` -gt 0 ]; then
    COLUMNS_PRIV="    UPDATE mysql.columns_priv set db='$3' WHERE db='$2';"
fi
if [ `mysql -h $1 -e "select count(*) from mysql.procs_priv where db='$2'" -sss` -gt 0 ]; then
    PROCS_PRIV="    UPDATE mysql.procs_priv set db='$3' WHERE db='$2';"
fi
if [ `mysql -h $1 -e "select count(*) from mysql.tables_priv where db='$2'" -sss` -gt 0 ]; then
    TABLES_PRIV="    UPDATE mysql.tables_priv set db='$3' WHERE db='$2';"
fi
if [ `mysql -h $1 -e "select count(*) from mysql.db where db='$2'" -sss` -gt 0 ]; then
    DB_PRIV="    UPDATE mysql.db set db='$3' WHERE db='$2';"
fi
if [ -n "$COLUMNS_PRIV" ] || [ -n "$PROCS_PRIV" ] || [ -n "$TABLES_PRIV" ] || [ -n "$DB_PRIV" ]; then
    echo "IF YOU WANT TO RENAME the GRANTS YOU NEED TO RUN ALL OUTPUT BELOW:"
    if [ -n "$COLUMNS_PRIV" ]; then echo "$COLUMNS_PRIV"; fi
    if [ -n "$PROCS_PRIV" ]; then echo "$PROCS_PRIV"; fi
    if [ -n "$TABLES_PRIV" ]; then echo "$TABLES_PRIV"; fi
    if [ -n "$DB_PRIV" ]; then echo "$DB_PRIV"; fi
    echo "    flush privileges;"
fi

mysqldump exports only one table

Quoting this link: http://steveswanson.wordpress.com/2009/04/21/exporting-and-importing-an-individual-mysql-table/

  • Exporting the Table

To export the table run the following command from the command line:

mysqldump -p --user=username dbname tableName > tableName.sql

This will export the tableName to the file tableName.sql.

  • Importing the Table

To import the table run the following command from the command line:

mysql -u username -p -D dbname < tableName.sql

The path to the tableName.sql needs to be prepended with the absolute path to that file. At this point the table will be imported into the DB.

How to convert all tables from MyISAM into InnoDB?

Use this as a sql query in your phpMyAdmin

SELECT CONCAT('ALTER TABLE ',table_schema,'.',table_name,' engine=InnoDB;') 
FROM information_schema.tables 
WHERE engine = 'MyISAM';

Database corruption with MariaDB : Table doesn't exist in engine

This theme required awhile to find results and reasons:

using MaiaDB 5.4. via SuSE-LINUX tumblweed

  1. some files in the appointed directory havn't been necessary in any direct relation with mariadb. I.e: I placed some hints, a text-file, some bakup-copys somewhere in the same appointed directory for mysql mariadb and this caused endless error-messages and blocking the server from starting. Mariadb appears to be very sensible and hostile with the presence of other files not beeing database files(comments,backups,experimantal files etc) .

  2. using libreoffice as client then there already this generated much problems with the creation and working on a database and caused some crashes.The crashes eventually produced bad tables.

  3. May be because of that or may be because of the presence of not yet deleted but unusable tables !! the mysql mariadb server crashed and didn't want to do it' job not even start.

Error message always same : "Table 'some.table' doesn't exist in engine"

But when it started then tables appeared as normal, but it was unpossible to work on them.

So what to do without a more precise Error Message ?? The unusable tables showed up with: "CHECK TABLE" or on the command line of the system with "mysqlcheck " So I deleted by filemanager or on the system-level as root or as allowed user all the questionable files and then problem was solved.

Proposal: the Error Message could be a bit more precisely for example: "corrupted tables" (which can be found by CHECK TABLE, but only if the server is running) or by mysqlcheck even whe server is not running - but here are other disturbing files like hints/bakups a.s.o not visible.

ANYWAY it helped a lot to have backup-copies of the original database-files on a backup volume. This helped to check out and test it again and again until solution was found.

Good luck all - Herbert

Bogus foreign key constraint fail

Maybe you received an error when working with this table before. You can rename the table and try to remove it again.

ALTER TABLE `area` RENAME TO `area2`;
DROP TABLE IF EXISTS `area2`;

MyISAM versus InnoDB

For that ratio of read/writes I would guess InnoDB will perform better. Since you are fine with dirty reads, you might (if you afford) replicate to a slave and let all your reads go to the slave. Also, consider inserting in bulk, rather than one record at a time.

MySQL foreign key constraints, cascade delete

I got confused by the answer to this question, so I created a test case in MySQL, hope this helps

-- Schema
CREATE TABLE T1 (
    `ID` int not null auto_increment,
    `Label` varchar(50),
    primary key (`ID`)
);

CREATE TABLE T2 (
    `ID` int not null auto_increment,
    `Label` varchar(50),
    primary key (`ID`)
);

CREATE TABLE TT (
    `IDT1` int not null,
    `IDT2` int not null,
    primary key (`IDT1`,`IDT2`)
);

ALTER TABLE `TT`
    ADD CONSTRAINT `fk_tt_t1` FOREIGN KEY (`IDT1`) REFERENCES `T1`(`ID`) ON DELETE CASCADE,
    ADD CONSTRAINT `fk_tt_t2` FOREIGN KEY (`IDT2`) REFERENCES `T2`(`ID`) ON DELETE CASCADE;

-- Data
INSERT INTO `T1` (`Label`) VALUES ('T1V1'),('T1V2'),('T1V3'),('T1V4');
INSERT INTO `T2` (`Label`) VALUES ('T2V1'),('T2V2'),('T2V3'),('T2V4');
INSERT INTO `TT` (`IDT1`,`IDT2`) VALUES
(1,1),(1,2),(1,3),(1,4),
(2,1),(2,2),(2,3),(2,4),
(3,1),(3,2),(3,3),(3,4),
(4,1),(4,2),(4,3),(4,4);

-- Delete
DELETE FROM `T2` WHERE `ID`=4; -- Delete one field, all the associated fields on tt, will be deleted, no change in T1
TRUNCATE `T2`; -- Can't truncate a table with a referenced field
DELETE FROM `T2`; -- This will do the job, delete all fields from T2, and all associations from TT, no change in T1

How can I check MySQL engine type for a specific table?

SHOW CREATE TABLE <tablename>;

Less parseable but more readable than SHOW TABLE STATUS.

#1025 - Error on rename of './database/#sql-2e0f_1254ba7' to './database/table' (errno: 150)

For those who are getting to this question via google... this error can also happen if you try to rename a field that is acting as a foreign key.

Is there a REAL performance difference between INT and VARCHAR primary keys?

As usual, there are no blanket answers. 'It depends!' and I am not being facetious. My understanding of the original question was for keys on small tables - like Country (integer id or char/varchar code) being a foreign key to a potentially huge table like address/contact table.

There are two scenarios here when you want data back from the DB. First is a list/search kind of query where you want to list all the contacts with state and country codes or names (ids will not help and hence will need a lookup). The other is a get scenario on primary key which shows a single contact record where the name of the state, country needs to be shown.

For the latter get, it probably does not matter what the FK is based on since we are bringing together tables for a single record or a few records and on key reads. The former (search or list) scenario may be impacted by our choice. Since it is required to show country (at least a recognizable code and perhaps even the search itself includes a country code), not having to join another table through a surrogate key can potentially (I am just being cautious here because I have not actually tested this, but seems highly probable) improve performance; notwithstanding the fact that it certainly helps with the search.

As codes are small in size - not more than 3 chars usually for country and state, it may be okay to use the natural keys as foreign keys in this scenario.

The other scenario where keys are dependent on longer varchar values and perhaps on larger tables; the surrogate key probably has the advantage.

MySQL InnoDB not releasing disk space after deleting data rows from table

There are several ways to reclaim diskspace after deleting data from table for MySQL Inodb engine

If you don't use innodb_file_per_table from the beginning, dumping all data, delete all file, recreate database and import data again is only way ( check answers of FlipMcF above )

If you are using innodb_file_per_table, you may try

  1. If you can delete all data truncate command will delete data and reclaim diskspace for you.
  2. Alter table command will drop and recreate table so it can reclaim diskspace. Therefore after delete data, run alter table that change nothing to release hardisk ( ie: table TBL_A has charset uf8, after delete data run ALTER TABLE TBL_A charset utf8 -> this command change nothing from your table but It makes mysql recreate your table and regain diskspace
  3. Create TBL_B like TBL_A . Insert select data you want to keep from TBL_A into TBL_B. Drop TBL_A, and rename TBL_B to TBL_A. This way is very effective if TBL_A and data that needed to delete is big (delete command in MySQL innodb is very bad performance)

Howto: Clean a mysql InnoDB storage engine?

The InnoDB engine does not store deleted data. As you insert and delete rows, unused space is left allocated within the InnoDB storage files. Over time, the overall space will not decrease, but over time the 'deleted and freed' space will be automatically reused by the DB server.

You can further tune and manage the space used by the engine through an manual re-org of the tables. To do this, dump the data in the affected tables using mysqldump, drop the tables, restart the mysql service, and then recreate the tables from the dump files.

How to debug Lock wait timeout exceeded on MySQL?

The big problem with this exception is that its usually not reproducible in a test environment and we are not around to run innodb engine status when it happens on prod. So in one of the projects I put the below code into a catch block for this exception. That helped me catch the engine status when the exception happened. That helped a lot.

Statement st = con.createStatement();
ResultSet rs =  st.executeQuery("SHOW ENGINE INNODB STATUS");
while(rs.next()){
    log.info(rs.getString(1));
    log.info(rs.getString(2));
    log.info(rs.getString(3));
}

Unable to make the session state request to the session state server

Check that:

stateConnectionString="tcpip=server:port"

is correct. Also please check that default port (42424) is available and your system does not have a firewall that is blocking the port on your system

Placeholder in UITextView

I made my own version of the subclass of 'UITextView'. I liked Sam Soffes's idea of using the notifications, but I didn't liked the drawRect: overwrite. Seems overkill to me. I think I made a very clean implementation.

You can look at my subclass here. A demo project is also included.

Parse JSON from JQuery.ajax success data

parse and convert it to js object that's it.

success: function(response) {
    var content = "";
    var jsondata = JSON.parse(response);
    for (var x = 0; x < jsonData.length; x++) {
        content += jsondata[x].Id;
        content += "<br>";
        content += jsondata[x].Name;
        content += "<br>";
    }
    $("#ProductList").append(content);
}

How to POST JSON request using Apache HttpClient?

For Apache HttpClient 4.5 or newer version:

    CloseableHttpClient httpclient = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://targethost/login");
    String JSON_STRING="";
    HttpEntity stringEntity = new StringEntity(JSON_STRING,ContentType.APPLICATION_JSON);
    httpPost.setEntity(stringEntity);
    CloseableHttpResponse response2 = httpclient.execute(httpPost);

Note:

1 in order to make the code compile, both httpclient package and httpcore package should be imported.

2 try-catch block has been ommitted.

Reference: appache official guide

the Commons HttpClient project is now end of life, and is no longer being developed. It has been replaced by the Apache HttpComponents project in its HttpClient and HttpCore modules

How to add a jar in External Libraries in android studio

  1. Create libs folder under app folder and copy jar file into it.
  2. Add following line to dependcies in app build.gradle file:
implementation fileTree(include: '*.jar', dir: 'libs')

Does MS SQL Server's "between" include the range boundaries?

I've always used this:

WHERE myDate BETWEEN startDate AND (endDate+1)

LEFT JOIN vs. LEFT OUTER JOIN in SQL Server

There are mainly three types of JOIN

  1. Inner: fetches data, that are present in both tables
    • Only JOIN means INNER JOIN
  2. Outer: are of three types

    • LEFT OUTER - - fetches data present only in left table & matching condition
    • RIGHT OUTER - - fetches data present only in right table & matching condition
    • FULL OUTER - - fetches data present any or both table
    • (LEFT or RIGHT or FULL) OUTER JOIN can be written w/o writing "OUTER"
  3. Cross Join: joins everything to everything

Get folder name from full file path

I think you want to get parent folder name from file path. It is easy to get. One way is to create a FileInfo type object and use its Directory property.

Example:

FileInfo fInfo = new FileInfo("c:\projects\roott\wsdlproj\devlop\beta2\text\abc.txt");

String dirName = fInfo.Directory.Name;

How to get the date and time values in a C program?

#include<stdio.h>
using namespace std;

int main()
{
printf("%s",__DATE__);
printf("%s",__TIME__);

return 0;
}

How to create an Array, ArrayList, Stack and Queue in Java?

Just a small correction to the first answer in this thread.

Even for Stack, you need to create new object with generics if you are using Stack from java util packages.

Right usage:
    Stack<Integer> s = new Stack<Integer>();
    Stack<String> s1 = new Stack<String>();

    s.push(7);
    s.push(50);

    s1.push("string");
    s1.push("stack");

if used otherwise, as mentioned in above post, which is:

    /*
    Stack myStack = new Stack();
    // add any type of elements (String, int, etc..)
    myStack.push("Hello");
    myStack.push(1);
    */

Although this code works fine, has unsafe or unchecked operations which results in error.

How do I multiply each element in a list by a number?

You can do it in-place like so:

 l = [1, 2, 3, 4, 5]
 l[:] = [x * 5 for x in l]

This requires no additional imports and is very pythonic.

Show constraints on tables command

You can use this:

select
    table_name,column_name,referenced_table_name,referenced_column_name
from
    information_schema.key_column_usage
where
    referenced_table_name is not null
    and table_schema = 'my_database' 
    and table_name = 'my_table'

Or for better formatted output use this:

select
    concat(table_name, '.', column_name) as 'foreign key',  
    concat(referenced_table_name, '.', referenced_column_name) as 'references'
from
    information_schema.key_column_usage
where
    referenced_table_name is not null
    and table_schema = 'my_database' 
    and table_name = 'my_table'

How do I execute external program within C code in linux with arguments?

How about like this:

char* cmd = "./foo 1 2 3";
system(cmd);

Declaring and initializing a string array in VB.NET

I believe you need to specify "Option Infer On" for this to work.

Option Infer allows the compiler to make a guess at what is being represented by your code, thus it will guess that {"stuff"} is an array of strings. With "Option Infer Off", {"stuff"} won't have any type assigned to it, ever, and so it will always fail, without a type specifier.

Option Infer is, I think On by default in new projects, but Off by default when you migrate from earlier frameworks up to 3.5.

Opinion incoming:

Also, you mention that you've got "Option Explicit Off". Please don't do this.

Setting "Option Explicit Off" means that you don't ever have to declare variables. This means that the following code will silently and invisibly create the variable "Y":

Dim X as Integer
Y = 3

This is horrible, mad, and wrong. It creates variables when you make typos. I keep hoping that they'll remove it from the language.

How to write console output to a txt file

PrintWriter out = null;
try {
    out = new PrintWriter(new FileWriter("C:\\testing.txt"));
    } catch (IOException e) {
            e.printStackTrace();
    }
out.println("output");
out.close();

I am using absolute path for the FileWriter. It is working for me like a charm. Also Make sure the file is present in the location. Else It will throw a FileNotFoundException. This method does not create a new file in the target location if the file is not found.

Vue.js redirection to another page

So, what I was looking for was only where to put the window.location.href and the conclusion I came to was that the best and fastest way to redirect is in routes (that way, we do not wait for anything to load before we redirect).

Like this:

routes: [
    {
        path: "/",
        name: "ExampleRoot",
        component: exampleComponent,
        meta: {
            title: "_exampleTitle"
        },
        beforeEnter: () => {
            window.location.href = 'https://www.myurl.io';
        }
    }]

Maybe it will help someone..

How to pass parameters using ui-sref in ui-router to controller

You simply misspelled $stateParam, it should be $stateParams (with an s). That's why you get undefined ;)

Getting a POST variable

In addition to using Request.Form and Request.QueryString and depending on your specific scenario, it may also be useful to check the Page's IsPostBack property.

if (Page.IsPostBack)
{
  // HTTP Post
}
else
{
  // HTTP Get
}

jquery, domain, get URL

You can use below codes for get different parameters of Current URL

alert("document.URL : "+document.URL);
alert("document.location.href : "+document.location.href);
alert("document.location.origin : "+document.location.origin);
alert("document.location.hostname : "+document.location.hostname);
alert("document.location.host : "+document.location.host);
alert("document.location.pathname : "+document.location.pathname);

laravel the requested url was not found on this server

Make sure you have mod_rewrite enabled.

restart apache

and clear cookies of your browser for read again at .htaccess

Is there a query language for JSON?

You could use linq.js.

This allows to use aggregations and selectings from a data set of objects, as other structures data.

_x000D_
_x000D_
var data = [{ x: 2, y: 0 }, { x: 3, y: 1 }, { x: 4, y: 1 }];_x000D_
_x000D_
// SUM(X) WHERE Y > 0     -> 7_x000D_
console.log(Enumerable.From(data).Where("$.y > 0").Sum("$.x"));_x000D_
_x000D_
// LIST(X) WHERE Y > 0    -> [3, 4]_x000D_
console.log(Enumerable.From(data).Where("$.y > 0").Select("$.x").ToArray());
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/linq.js/2.2.0.2/linq.js"></script>
_x000D_
_x000D_
_x000D_

How to get the EXIF data from a file using C#

Image class has PropertyItems and PropertyIdList properties. You can use them.

IOException: The process cannot access the file 'file path' because it is being used by another process

I'm using FileStream and having same issue.. When ever Two request try to read same file it throw this exception.

solution use FileShare

using FileStream fs = System.IO.File.Open(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);

I'm Just Reading a file concurrently FileShare.Read solve my issue.

Use JAXB to create Object from XML String

There is no unmarshal(String) method. You should use a Reader:

Person person = (Person) unmarshaller.unmarshal(new StringReader("xml string"));

But usually you are getting that string from somewhere, for example a file. If that's the case, better pass the FileReader itself.

When to use LinkedList over ArrayList in Java?

Let's compare LinkedList and ArrayList w.r.t. below parameters:

1. Implementation

ArrayList is the resizable array implementation of list interface , while

LinkedList is the Doubly-linked list implementation of the list interface.


2. Performance

  • get(int index) or search operation

    ArrayList get(int index) operation runs in constant time i.e O(1) while

    LinkedList get(int index) operation run time is O(n) .

    The reason behind ArrayList being faster than LinkedList is that ArrayList uses an index based system for its elements as it internally uses an array data structure, on the other hand,

    LinkedList does not provide index-based access for its elements as it iterates either from the beginning or end (whichever is closer) to retrieve the node at the specified element index.

  • insert() or add(Object) operation

    Insertions in LinkedList are generally fast as compare to ArrayList. In LinkedList adding or insertion is O(1) operation .

    While in ArrayList, if the array is the full i.e worst case, there is an extra cost of resizing array and copying elements to the new array, which makes runtime of add operation in ArrayList O(n), otherwise it is O(1).

  • remove(int) operation

    Remove operation in LinkedList is generally the same as ArrayList i.e. O(n).

    In LinkedList, there are two overloaded remove methods. one is remove() without any parameter which removes the head of the list and runs in constant time O(1). The other overloaded remove method in LinkedList is remove(int) or remove(Object) which removes the Object or int passed as a parameter. This method traverses the LinkedList until it found the Object and unlink it from the original list. Hence this method runtime is O(n).

    While in ArrayList remove(int) method involves copying elements from the old array to new updated array, hence its runtime is O(n).


3. Reverse Iterator

LinkedList can be iterated in reverse direction using descendingIterator() while

there is no descendingIterator() in ArrayList , so we need to write our own code to iterate over the ArrayList in reverse direction.


4. Initial Capacity

If the constructor is not overloaded, then ArrayList creates an empty list of initial capacity 10, while

LinkedList only constructs the empty list without any initial capacity.


5. Memory Overhead

Memory overhead in LinkedList is more as compared to ArrayList as a node in LinkedList needs to maintain the addresses of the next and previous node. While

In ArrayList each index only holds the actual object(data).


Source

Find value in an array

I'm guessing that you're trying to find if a certain value exists inside the array, and if that's the case, you can use Array#include?(value):

a = [1,2,3,4,5]
a.include?(3)   # => true
a.include?(9)   # => false

If you mean something else, check the Ruby Array API

Java Scanner class reading strings

The reason for the error is that the nextInt only pulls the integer, not the newline. If you add a in.nextLine() before your for loop, it will eat the empty new line and allow you to enter 3 names.

int nnames;
String names[];

System.out.print("How many names are you going to save: ");
Scanner in = new Scanner(System.in);
nnames = in.nextInt();

names = new String[nnames];
in.nextLine();
for (int i = 0; i < names.length; i++){
        System.out.print("Type a name: ");
        names[i] = in.nextLine();
}

or just read the line and parse the value as an Integer.

int nnames;
String names[];

System.out.print("How many names are you going to save: ");
Scanner in = new Scanner(System.in);
nnames = Integer.parseInt(in.nextLine().trim());

names = new String[nnames];
for (int i = 0; i < names.length; i++){
        System.out.print("Type a name: ");
        names[i] = in.nextLine();
}

Timestamp to human readable format

use Date.prototype.toLocaleTimeString() as documented here

please note the locale example en-US in the url.

What is the difference between % and %% in a cmd file?

(Explanation in more details can be found in an archived Microsoft KB article.)

Three things to know:

  1. The percent sign is used in batch files to represent command line parameters: %1, %2, ...
  2. Two percent signs with any characters in between them are interpreted as a variable:

    echo %myvar%

  3. Two percent signs without anything in between (in a batch file) are treated like a single percent sign in a command (not a batch file): %%f

Why's that?

For example, if we execute your (simplified) command line

FOR /f %f in ('dir /b .') DO somecommand %f

in a batch file, rule 2 would try to interpret

%f in ('dir /b .') DO somecommand %

as a variable. In order to prevent that, you have to apply rule 3 and escape the % with an second %:

FOR /f %%f in ('dir /b .') DO somecommand %%f

Avoid trailing zeroes in printf()

Hit the same issue, double precision is 15 decimal, and float precision is 6 decimal, so I wrote to 2 functions for them separately

#include <stdio.h>
#include <math.h>
#include <string>
#include <string.h>

std::string doublecompactstring(double d)
{
    char buf[128] = {0};
    if (isnan(d))
        return "NAN";
    sprintf(buf, "%.15f", d);
    // try to remove the trailing zeros
    size_t ccLen = strlen(buf);
    for(int i=(int)(ccLen -1);i>=0;i--)
    {
        if (buf[i] == '0')
            buf[i] = '\0';
        else
            break;
    }

    return buf;
}

std::string floatcompactstring(float d)
{
    char buf[128] = {0};
    if (isnan(d))
        return "NAN";
    sprintf(buf, "%.6f", d);
    // try to remove the trailing zeros
    size_t ccLen = strlen(buf);
    for(int i=(int)(ccLen -1);i>=0;i--)
    {
        if (buf[i] == '0')
            buf[i] = '\0';
        else
            break;
    }

    return buf;
}

int main(int argc, const char* argv[])
{
    double a = 0.000000000000001;
    float  b = 0.000001f;

    printf("a: %s\n", doublecompactstring(a).c_str());
    printf("b: %s\n", floatcompactstring(b).c_str());
    return 0;
}

output is

a: 0.000000000000001
b: 0.000001

Difference between Visual Basic 6.0 and VBA

Actually VBA can be used to compile DLLs. The Office 2000 and Office XP Developer editions included a VBA editor that could be used for making DLLs for use as COM Addins.

This functionality was removed in later versions (2003 and 2007) with the advent of the VSTO (VS Tools for Office) software, although obviously you could still create COM addins in a similar fashion without the use of VSTO (or VS.Net) by using VB6 IDE.

How do you overcome the HTML form nesting limitation?

HTML5 has an idea of "form owner" - the "form" attribute for input elements. It allows to emulate nested forms and will solve the issue.

Do Swift-based applications work on OS X 10.9/iOS 7 and lower?

Apple has announced that Swift apps will be backward compatible with iOS 7 and OS X Mavericks. The WWDC app is written in Swift.

C Program to find day of week given date

This one works: I took January 2006 as a reference. (It is a Sunday)

int isLeapYear(int year) {

     if(((year%4==0)&&(year%100!=0))||((year%400==0))) 
        return 1;
     else 
        return 0;

 }

int isDateValid(int dd,int mm,int yyyy) {

    int isValid=-1; 
    if(mm<0||mm>12) {
        isValid=-1;
    }
    else {

    if((mm==1)||(mm==3)||(mm==5)||(mm==7)||(mm==8)||(mm==10)||(mm==12)) {
           if((dd>0)&&(dd<=31))
             isValid=1;
    }  else if((mm==4)||(mm==6)||(mm==9)||(mm==11)) {
         if((dd>0)&&(dd<=30))
             isValid=1;
    }  else {
             if(isLeapYear(yyyy)){
                 if((dd>0)&&dd<30)
                     isValid=1;
             } else {
                   if((dd>0)&&dd<29)
                     isValid=1;
             }
        }  



    }
               return isValid;



 }


int calculateDayOfWeek(int dd,int mm,int yyyy)  {

                if(isDateValid(dd,mm,yyyy)==-1) {
                    return -1;
                }

                 int days=0;
                  int i; 

                   for(i=yyyy-1;i>=2006;i--) {
                         days+=(365+isLeapYear(i));

                     }
                     printf("days after years is %d\n",days);

                   for(i=mm-1;i>0;i--) {

                       if((i==1)||(i==3)||(i==5)||(i==7)||(i==8)||(i==10)) {

                           days+=31;
                       }
                       else if((i==4)||(i==6)||(i==9)||(i==11)) {
                           days+=30;
                       } else {

                           days+= (28+isLeapYear(i));

                       }


                   }
                       printf("days after months is %d\n",days);

                   days+=dd;

                   printf("days after days is %d\n",days);

                   return ((days-1)%7);                


              }

Django Multiple Choice Field / Checkbox Select Multiple

The models.CharField is a CharField representation of one of the choices. What you want is a set of choices. This doesn't seem to be implemented in django (yet).

You could use a many to many field for it, but that has the disadvantage that the choices have to be put in a database. If you want to use hard coded choices, this is probably not what you want.

There is a django snippet at http://djangosnippets.org/snippets/1200/ that does seem to solve your problem, by implementing a ModelField MultipleChoiceField.

Selecting multiple columns/fields in MySQL subquery

Yes, you can do this. The knack you need is the concept that there are two ways of getting tables out of the table server. One way is ..

FROM TABLE A

The other way is

FROM (SELECT col as name1, col2 as name2 FROM ...) B

Notice that the select clause and the parentheses around it are a table, a virtual table.

So, using your second code example (I am guessing at the columns you are hoping to retrieve here):

SELECT a.attr, b.id, b.trans, b.lang
FROM attribute a
JOIN (
 SELECT at.id AS id, at.translation AS trans, at.language AS lang, a.attribute
 FROM attributeTranslation at
) b ON (a.id = b.attribute AND b.lang = 1)

Notice that your real table attribute is the first table in this join, and that this virtual table I've called b is the second table.

This technique comes in especially handy when the virtual table is a summary table of some kind. e.g.

SELECT a.attr, b.id, b.trans, b.lang, c.langcount
FROM attribute a
JOIN (
 SELECT at.id AS id, at.translation AS trans, at.language AS lang, at.attribute
 FROM attributeTranslation at
) b ON (a.id = b.attribute AND b.lang = 1)
JOIN (
 SELECT count(*) AS langcount,  at.attribute
 FROM attributeTranslation at
 GROUP BY at.attribute
) c ON (a.id = c.attribute)

See how that goes? You've generated a virtual table c containing two columns, joined it to the other two, used one of the columns for the ON clause, and returned the other as a column in your result set.

Calculating percentile of dataset column

table_ages <- subset(infert, select=c("age"))
summary(table_ages)
#            age       
#  Min.   :21.00  
#  1st Qu.:28.00  
#  Median :31.00  
#  Mean   :31.50  
#  3rd Qu.:35.25  
#  Max.   :44.00  

This is probably what they're looking for. summary(...) applied to a numeric returns the min, max, mean, median, and 25th and 75th percentile of the data.

Note that

summary(infert$age)
#    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
#   21.00   28.00   31.00   31.50   35.25   44.00 

The numbers are the same but the format is different. This is because table_ages is a data frame with one column (ages), whereas infert$age is a numeric vector. Try typing summary(infert).

How can I stage and commit all files, including newly added files, using a single command?

I have in my config two aliases:

alias.foo=commit -a -m 'none'
alias.coa=commit -a -m

if I am too lazy I just commit all changes with

git foo

and just to do a quick commit

git coa "my changes are..."

coa stands for "commit all"

html "data-" attribute as javascript parameter

The easiest way to get data-* attributes is with element.getAttribute():

onclick="fun(this.getAttribute('data-uid'), this.getAttribute('data-name'), this.getAttribute('data-value'));"

DEMO: http://jsfiddle.net/pm6cH/


Although I would suggest just passing this to fun(), and getting the 3 attributes inside the fun function:

onclick="fun(this);"

And then:

function fun(obj) {
    var one = obj.getAttribute('data-uid'),
        two = obj.getAttribute('data-name'),
        three = obj.getAttribute('data-value');
}

DEMO: http://jsfiddle.net/pm6cH/1/


The new way to access them by property is with dataset, but that isn't supported by all browsers. You'd get them like the following:

this.dataset.uid
// and
this.dataset.name
// and
this.dataset.value

DEMO: http://jsfiddle.net/pm6cH/2/


Also note that in your HTML, there shouldn't be a comma here:

data-name="bbb",

References:

start MySQL server from command line on Mac OS Lion

111028 16:57:43 [ERROR] Fatal error: Please read "Security" section of the manual to find out how to run mysqld as root!

Have you set a root password for your mysql installation? This is different to your sudo root password. Try /usr/local/mysql/bin/mysql_secure_installation

Find all elements with a certain attribute value in jquery

You can use partial value of an attribute to detect a DOM element using (^) sign. For example you have divs like this:

<div id="abc_1"></div>
<div id="abc_2"></div>
<div id="xyz_3"></div>
<div id="xyz_4"></div>...

You can use the code:

var abc = $('div[id^=abc]')

This will return a DOM array of divs which have id starting with abc:

<div id="abc_1"></div>
<div id="abc_2"></div>

Here is the demo: http://jsfiddle.net/mCuWS/

Under what conditions is a JSESSIONID created?

JSESSIONID cookie is created/sent when session is created. Session is created when your code calls request.getSession() or request.getSession(true) for the first time. If you just want to get the session, but not create it if it doesn't exist, use request.getSession(false) -- this will return you a session or null. In this case, new session is not created, and JSESSIONID cookie is not sent. (This also means that session isn't necessarily created on first request... you and your code are in control when the session is created)

Sessions are per-context:

SRV.7.3 Session Scope

HttpSession objects must be scoped at the application (or servlet context) level. The underlying mechanism, such as the cookie used to establish the session, can be the same for different contexts, but the object referenced, including the attributes in that object, must never be shared between contexts by the container.

(Servlet 2.4 specification)

Update: Every call to JSP page implicitly creates a new session if there is no session yet. This can be turned off with the session='false' page directive, in which case session variable is not available on JSP page at all.

What is an .inc and why use it?

It has no meaning, it is just a file extension. It is some people's convention to name files with a .inc extension if that file is designed to be included by other PHP files, but it is only convention.

It does have a possible disadvantage which is that servers normally are not configured to parse .inc files as php, so if the file sits in your web root and your server is configured in the default way, a user could view your php source code in the .inc file by visiting the URL directly.

Its only possible advantage is that it is easy to identify which files are used as includes. Although simply giving them a .php extension and placing them in an includes folder has the same effect without the disadvantage mentioned above.

How to initialize a list of strings (List<string>) with many string values

One really cool feature is that list initializer works just fine with custom classes too: you have just to implement the IEnumerable interface and have a method called Add.

So for example if you have a custom class like this:

class MyCustomCollection : System.Collections.IEnumerable
{
    List<string> _items = new List<string>();

    public void Add(string item)
    {
        _items.Add(item);
    }

    public IEnumerator GetEnumerator()
    {
        return _items.GetEnumerator();
    }
}

this will work:

var myTestCollection = new MyCustomCollection()
{
    "item1",
    "item2"
}

Notification not showing in Oreo

First of all, if you dont know, from Android Oreo i.e API level 26 it's compulsory that notifications are resgitered with a channel.

In that case many tutorials might confuse you because they show different example for notification above oreo and below.

So here is is a common code which runs on both above and below oreo:

String CHANNEL_ID = "MESSAGE";
String CHANNEL_NAME = "MESSAGE";

NotificationManagerCompat manager = NotificationManagerCompat.from(MainActivity.this);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    NotificationChannel channel = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME,
    NotificationManager.IMPORTANCE_DEFAULT);
    manager.createNotificationChannel(channel);
}

Notification notification = new NotificationCompat.Builder(MainActivity.this,CHANNEL_ID)
        .setSmallIcon(R.drawable.ic_android_black_24dp)
        .setContentTitle(TitleTB.getText().toString())
        .setContentText(MessageTB.getText().toString())
        .build();
manager.notify(getRandomNumber(), notification); // In case you pass a number instead of getRandoNumber() then the new notification will override old one and you wont have more then one notification so to do so u need to pass unique number every time so here is how we can do it by "getRandoNumber()"
private static int getRandomNumber() {
    Date dd= new Date();
    SimpleDateFormat ft =new SimpleDateFormat ("mmssSS");
    String s=ft.format(dd);
    return Integer.parseInt(s);
}

Video Tutorial: YOUTUBE VIDEO

In case you want to download this demo: GitHub Link

How to compile C++ under Ubuntu Linux?

You should use g++, not gcc, to compile C++ programs.

For this particular program, I just typed

make avishay

and let make figure out the rest. Gives your executable a decent name, too, instead of a.out.

What's the best way to override a user agent CSS stylesheet rule that gives unordered-lists a 1em margin?

I had the same issues but nothing worked. What I did was I added this to the selector:

-webkit-appearance: none;
-moz-appearance: none;
appearance: none;

What is move semantics?

Suppose you have a function that returns a substantial object:

Matrix multiply(const Matrix &a, const Matrix &b);

When you write code like this:

Matrix r = multiply(a, b);

then an ordinary C++ compiler will create a temporary object for the result of multiply(), call the copy constructor to initialise r, and then destruct the temporary return value. Move semantics in C++0x allow the "move constructor" to be called to initialise r by copying its contents, and then discard the temporary value without having to destruct it.

This is especially important if (like perhaps the Matrix example above), the object being copied allocates extra memory on the heap to store its internal representation. A copy constructor would have to either make a full copy of the internal representation, or use reference counting and copy-on-write semantics interally. A move constructor would leave the heap memory alone and just copy the pointer inside the Matrix object.

Forward X11 failed: Network error: Connection refused

fill in the "X display location" did not work for me. but install MobaXterm did the job.

Read file from aws s3 bucket using node fs

var fileStream = fs.createWriteStream('/path/to/file.jpg');
var s3Stream = s3.getObject({Bucket: 'myBucket', Key: 'myImageFile.jpg'}).createReadStream();

// Listen for errors returned by the service
s3Stream.on('error', function(err) {
    // NoSuchKey: The specified key does not exist
    console.error(err);
});

s3Stream.pipe(fileStream).on('error', function(err) {
    // capture any errors that occur when writing data to the file
    console.error('File Stream:', err);
}).on('close', function() {
    console.log('Done.');
});

Reference: https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/requests-using-stream-objects.html

Excel column number from column name

Write and run the following code in the Immediate Window

?cells(,"type the column name here").column

For example ?cells(,"BYL").column will return 2014. The code is case-insensitive, hence you may write ?cells(,"byl").column and the output will still be the same.

jquery count li elements inside ul -> length?

You have to count the li elements not the ul elements:

if ( $('#menu ul li').length > 1 ) {

If you need every UL element containing at least two LI elements, use the filter function:

$('#menu ul').filter(function(){ return $(this).children("li").length > 1 })

You can also use that in your condition:

if ( $('#menu ul').filter(function(){ return $(this).children("li").length > 1 }).length) {

How can I get a vertical scrollbar in my ListBox?

ListBox already contains ScrollViewer. By default the ScrollBar will show up when there is more content than space. But some containers resize themselves to accommodate their contents (e.g. StackPanel), so there is never "more content than space". In such cases, the ListBox is always given as much space as is needed for the content.

In order to calculate the condition of having more content than space, the size should be known. Make sure your ListBox has a constrained size, either by setting the size explicitly on the ListBox element itself, or from the host panel.

In case the host panel is vertical StackPanel and you want VerticalScrollBar you must set the Height on ListBox itself. For other types of containers, e.g. Grid, the ListBox can be constrained by the container. For example, you can change your original code to look like this:

<Grid Name="grid1">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="2*"></RowDefinition>
            <RowDefinition Height="*"></RowDefinition>
        </Grid.RowDefinitions>
        <ListBox Grid.Row="0" Name="lstFonts" Margin="3"
                 ItemsSource="{x:Static Fonts.SystemFontFamilies}"/>
    </Grid>
</Grid>

Note that it is not just the immediate container that is important. In your example, the immediate container is a Grid, but because that Grid is contained by a StackPanel, the outer StackPanel is expanded to accommodate its immediate child Grid, such that that child can expand to accommodate its child (the ListBox).

If you constrain the height at any point — by setting the height of the ListBox, by setting the height of the inner Grid, or simply by making the outer container a Grid — then a vertical scroll bar will appear automatically any time there are too many list items to fit in the control.

Array inside a JavaScript Object?

var obj = {
 webSiteName: 'StackOverFlow',
 find: 'anything',
 onDays: ['sun'     // Object "obj" contains array "onDays" 
            ,'mon',
            'tue',
            'wed',
            'thu',
            'fri',
            'sat',
             {name : "jack", age : 34},
              // array "onDays"contains array object "manyNames"
             {manyNames : ["Narayan", "Payal", "Suraj"]}, //                 
           ]
};

How to make Regular expression into non-greedy?

You are right that greediness is an issue:

--A--Z--A--Z--
  ^^^^^^^^^^
     A.*Z

If you want to match both A--Z, you'd have to use A.*?Z (the ? makes the * "reluctant", or lazy).

There are sometimes better ways to do this, though, e.g.

A[^Z]*+Z

This uses negated character class and possessive quantifier, to reduce backtracking, and is likely to be more efficient.

In your case, the regex would be:

/(\[[^\]]++\])/

Unfortunately Javascript regex doesn't support possessive quantifier, so you'd just have to do with:

/(\[[^\]]+\])/

See also


Quick summary

*   Zero or more, greedy
*?  Zero or more, reluctant
*+  Zero or more, possessive

+   One or more, greedy
+?  One or more, reluctant
++  One or more, possessive

?   Zero or one, greedy
??  Zero or one, reluctant
?+  Zero or one, possessive

Note that the reluctant and possessive quantifiers are also applicable to the finite repetition {n,m} constructs.

Examples in Java:

System.out.println("aAoZbAoZc".replaceAll("A.*Z", "!"));  // prints "a!c"
System.out.println("aAoZbAoZc".replaceAll("A.*?Z", "!")); // prints "a!b!c"

System.out.println("xxxxxx".replaceAll("x{3,5}", "Y"));  // prints "Yx"
System.out.println("xxxxxx".replaceAll("x{3,5}?", "Y")); // prints "YY"

.ssh directory not being created

Is there a step missing?

Yes. You need to create the directory:

mkdir ${HOME}/.ssh

Additionally, SSH requires you to set the permissions so that only you (the owner) can access anything in ~/.ssh:

% chmod 700 ~/.ssh

Should the .ssh dir be generated when I use the ssh-keygen command?

No. This command generates an SSH key pair but will fail if it cannot write to the required directory:

% ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/xxx/.ssh/id_rsa): /Users/tmp/does_not_exist
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
open /Users/tmp/does_not_exist failed: No such file or directory.
Saving the key failed: /Users/tmp/does_not_exist.

Once you've created your keys, you should also restrict who can read those key files to just yourself:

% chmod -R go-wrx ~/.ssh/*

How do I get the directory from a file's full path?

You can use System.IO.Path.GetDirectoryName(fileName), or turn the path into a FileInfo using FileInfo.Directory.

If you're doing other things with the path, the FileInfo class may have advantages.

Solving "adb server version doesn't match this client" error

I had same problem since updated platfrom-tool to version 24 and not sure for root cause...(current adb version is 1.0.36)

Also try adb kill-server and adb start-server but problem still happened

but when I downgrade adb version to 1.0.32 everything work will

sorting integers in order lowest to highest java

if array.sort doesn't have what your looking for you can try this:

package drawFramePackage;
import java.awt.geom.AffineTransform;
import java.util.ArrayList;
import java.util.ListIterator;
import java.util.Random;
public class QuicksortAlgorithm {
    ArrayList<AffineTransform> affs;
    ListIterator<AffineTransform> li;
    Integer count, count2;
    /**
     * @param args
     */
    public static void main(String[] args) {
        new QuicksortAlgorithm();
    }
    public QuicksortAlgorithm(){
        count = new Integer(0);
        count2 = new Integer(1);
        affs = new ArrayList<AffineTransform>();
        for (int i = 0; i <= 128; i++){
            affs.add(new AffineTransform(1, 0, 0, 1, new Random().nextInt(1024), 0));
        }
        affs = arrangeNumbers(affs);
        printNumbers();
    }
    public ArrayList<AffineTransform> arrangeNumbers(ArrayList<AffineTransform> list){
        while (list.size() > 1 && count != list.size() - 1){
            if (list.get(count2).getTranslateX() > list.get(count).getTranslateX()){
                list.add(count, list.get(count2));
                list.remove(count2 + 1);
            }
            if (count2 == list.size() - 1){
                count++;
                count2 = count + 1;
            }
            else{
            count2++;
            }
        }
        return list;
    }
    public void printNumbers(){
        li = affs.listIterator();
        while (li.hasNext()){
            System.out.println(li.next());
        }
    }
}

element with the max height from a set of elements

Easiest and clearest way I'd say is:

var maxHeight = 0, maxHeightElement = null;
$('.panel').each(function(){
   if ($(this).height() > maxHeight) {
       maxHeight = $(this).height();
       maxHeightElement = $(this);
   }
});

Passing arrays as parameters in bash

Commenting on Ken Bertelson solution and answering Jan Hettich:

How it works

the takes_ary_as_arg descTable[@] optsTable[@] line in try_with_local_arys() function sends:

  1. This is actually creates a copy of the descTable and optsTable arrays which are accessible to the takes_ary_as_arg function.
  2. takes_ary_as_arg() function receives descTable[@] and optsTable[@] as strings, that means $1 == descTable[@] and $2 == optsTable[@].
  3. in the beginning of takes_ary_as_arg() function it uses ${!parameter} syntax, which is called indirect reference or sometimes double referenced, this means that instead of using $1's value, we use the value of the expanded value of $1, example:

    baba=booba
    variable=baba
    echo ${variable} # baba
    echo ${!variable} # booba
    

    likewise for $2.

  4. putting this in argAry1=("${!1}") creates argAry1 as an array (the brackets following =) with the expanded descTable[@], just like writing there argAry1=("${descTable[@]}") directly. the declare there is not required.

N.B.: It is worth mentioning that array initialization using this bracket form initializes the new array according to the IFS or Internal Field Separator which is by default tab, newline and space. in that case, since it used [@] notation each element is seen by itself as if he was quoted (contrary to [*]).

My reservation with it

In BASH, local variable scope is the current function and every child function called from it, this translates to the fact that takes_ary_as_arg() function "sees" those descTable[@] and optsTable[@] arrays, thus it is working (see above explanation).

Being that case, why not directly look at those variables themselves? It is just like writing there:

argAry1=("${descTable[@]}")

See above explanation, which just copies descTable[@] array's values according to the current IFS.

In summary

This is passing, in essence, nothing by value - as usual.

I also want to emphasize Dennis Williamson comment above: sparse arrays (arrays without all the keys defines - with "holes" in them) will not work as expected - we would loose the keys and "condense" the array.

That being said, I do see the value for generalization, functions thus can get the arrays (or copies) without knowing the names:

  • for ~"copies": this technique is good enough, just need to keep aware, that the indices (keys) are gone.
  • for real copies: we can use an eval for the keys, for example:

    eval local keys=(\${!$1})
    

and then a loop using them to create a copy. Note: here ! is not used it's previous indirect/double evaluation, but rather in array context it returns the array indices (keys).

  • and, of course, if we were to pass descTable and optsTable strings (without [@]), we could use the array itself (as in by reference) with eval. for a generic function that accepts arrays.

How to pass multiple values to single parameter in stored procedure

I think, below procedure help you to what you are looking for.

 CREATE PROCEDURE [dbo].[FindEmployeeRecord]
        @EmployeeID nvarchar(Max)
    AS
    BEGIN
    DECLARE @sqLQuery VARCHAR(MAX)
    Declare @AnswersTempTable Table
    (  
        EmpId int,         
        EmployeeName nvarchar (250),       
        EmployeeAddress nvarchar (250),  
        PostalCode nvarchar (50),
        TelephoneNo nvarchar (50),
        Email nvarchar (250),
        status nvarchar (50),  
        Sex nvarchar (50) 
    )

    Set @sqlQuery =
    'select e.EmpId,e.EmployeeName,e.Email,e.Sex,ed.EmployeeAddress,ed.PostalCode,ed.TelephoneNo,ed.status
    from Employee e
    join EmployeeDetail ed on e.Empid = ed.iEmpID
    where Convert(nvarchar(Max),e.EmpId) in ('+@EmployeeId+')
    order by EmpId'
    Insert into @AnswersTempTable
    exec (@sqlQuery)
    select * from @AnswersTempTable
    END

How to keep a git branch in sync with master

You are thinking in the right direction. Merge master with mobiledevicesupport continuously and merge mobiledevicesupport with master when mobiledevicesupport is stable. Each developer will have his own branch and can merge to and from either on master or mobiledevicesupport depending on their role.

React Native: Possible unhandled promise rejection

According to this post, you should enable it in XCode.

  1. Click on your project in the Project Navigator
  2. Open the Info tab
  3. Click on the down arrow left to the "App Transport Security Settings"
  4. Right click on "App Transport Security Settings" and select Add Row
  5. For created row set the key “Allow Arbitrary Loads“, type to boolean and value to YES.

enter image description here

ASP.NET DateTime Picker

Basic Date Picker Lite

This is the free version of their flagship product, but it contains a date and time picker native for asp.net.

How do I disable text selection with CSS or JavaScript?

I'm not sure if you can turn it off, but you can change the colors of it :)

myDiv::selection,
myDiv::-moz-selection,
myDiv::-webkit-selection {
    background:#000;
    color:#fff;
}

Then just match the colors to your "darky" design and see what happens :)

Converting a date string to a DateTime object using Joda Time library

An simple method :

public static DateTime transfStringToDateTime(String dateParam, Session session) throws NotesException {
    DateTime dateRetour;
    dateRetour = session.createDateTime(dateParam);                 

    return dateRetour;
}

HQL "is null" And "!= null" on an Oracle column

If you do want to use null values with '=' or '<>' operators you may find the

answer from @egallardo hier

very useful.

Short example for '=': The expression

WHERE t.field = :param

you refactor like this

WHERE ((:param is null and t.field is null) or t.field = :param)

Now you can set the parameter param either to some non-null value or to null:

query.setParameter("param", "Hello World"); // Works
query.setParameter("param", null);          // Works also

Python "TypeError: unhashable type: 'slice'" for encoding categorical data

While creating the matrix X and Y vector use values.

X=dataset.iloc[:,4].values
Y=dataset.iloc[:,0:4].values

It will definitely solve your problem.

Detecting input change in jQuery?

With HTML5 and without using jQuery, you can using the input event:

var input = document.querySelector('input');

input.addEventListener('input', function()
{
    console.log('input changed to: ', input.value);
});

This will fire each time the input's text changes.

Supported in IE9+ and other browsers.

Try it live in a jsFiddle here.

Selenium -- How to wait until page is completely loaded

There are two different ways to use delay in selenium one which is most commonly in use. Please try this:

driver.manage().timeouts().implicitlyWait(20, TimeUnit.SECONDS);

second one which you can use that is simply try catch method by using that method you can get your desire result.if you want example code feel free to contact me defiantly I will provide related code

Remove a prefix from a string

def remove_prefix(str, prefix):
    if str.startswith(prefix):
        return str[len(prefix):]
    else:
        return str

As an aside note, str is a bad name for a variable because it shadows the str type.

Multiple conditions with CASE statements

Another way based on amadan:

    SELECT * FROM [Purchasing].[Vendor] WHERE  

      ( (@url IS null OR @url = '' OR @url = 'ALL') and   PurchasingWebServiceURL LIKE '%')
    or

       ( @url = 'blank' and  PurchasingWebServiceURL = '')
    or
        (@url = 'fail' and  PurchasingWebServiceURL NOT LIKE '%treyresearch%')
    or( (@url not in ('fail','blank','','ALL') and @url is not null and 
          PurchasingWebServiceUrl Like '%'+@ur+'%') 
END

Lost connection to MySQL server during query?

The mysql docs have a whole page dedicated to this error: http://dev.mysql.com/doc/refman/5.0/en/gone-away.html

of note are

  • You can also get these errors if you send a query to the server that is incorrect or too large. If mysqld receives a packet that is too large or out of order, it assumes that something has gone wrong with the client and closes the connection. If you need big queries (for example, if you are working with big BLOB columns), you can increase the query limit by setting the server's max_allowed_packet variable, which has a default value of 1MB. You may also need to increase the maximum packet size on the client end. More information on setting the packet size is given in Section B.5.2.10, “Packet too large”.

  • You can get more information about the lost connections by starting mysqld with the --log-warnings=2 option. This logs some of the disconnected errors in the hostname.err file

Where are static methods and static variables stored in Java?

When we create a static variable or method it is stored in the special area on heap: PermGen(Permanent Generation), where it lays down with all the data applying to classes(non-instance data). Starting from Java 8 the PermGen became - Metaspace. The difference is that Metaspace is auto-growing space, while PermGen has a fixed Max size, and this space is shared among all of the instances. Plus the Metaspace is a part of a Native Memory and not JVM Memory.

You can look into this for more details.

Chrome doesn't delete session cookies

I had to both, unchecked, under advanced settings of Chrome :

  • 'Continue running background apps when Google Chrome is closed'
  • "Continue where I left off", "On startup"

XAMPP permissions on Mac OS X?

if you use one line folder or file

chmod 755 $(find /yourfolder -type d)
chmod 644 $(find /yourfolder -type f)

How to compare two columns in Excel and if match, then copy the cell next to it

try this formula in column E:

=IF( AND( ISNUMBER(D2), D2=G2), H2, "")

your error is the number test, ISNUMBER( ISMATCH(D2,G:G,0) )

you do check if ismatch is-a-number, (i.e. isNumber("true") or isNumber("false"), which is not!.

I hope you understand my explanation.

jQuery-- Populate select from json

I just used the javascript console in Chrome to do this. I replaced some of your stuff with placeholders.

var temp= ['one', 'two', 'three']; //'${temp}';
//alert(options);
var $select = $('<select>'); //$('#down');                        
$select.find('option').remove();                          
$.each(temp, function(key, value) {              
    $('<option>').val(key).text(value).appendTo($select);
});
console.log($select.html());

Output:

<option value="0">one</option><option value="1">two</option><option value="2">three</option>

However it looks like your json is probably actually a string because the following will end up doing what you describe. So make your JSON actual JSON not a string.

var temp= "['one', 'two', 'three']"; //'${temp}';
//alert(options);
var $select = $('<select>'); //$('#down');                        
$select.find('option').remove();                          
$.each(temp, function(key, value) {              
    $('<option>').val(key).text(value).appendTo($select);
});
console.log($select.html());

Error : Index was outside the bounds of the array.

//if i input 9 it should go to 8?

You still have to work with the elements of the array. You will count 8 elements when looping through the array, but they are still going to be array(0) - array(7).

Removing the textarea border in HTML

This one is great:

<style type="text/css">
textarea.test
{  
width: 100%;
height: 100%;
border-color: Transparent;     
}
</style>
<textarea class="test"></textarea>

How to display a range input slider vertically

_x000D_
_x000D_
.container {_x000D_
    border: 3px solid #eee;_x000D_
    margin: 10px;_x000D_
    padding: 10px;_x000D_
    float: left;_x000D_
    text-align: center;_x000D_
    max-width: 20%_x000D_
}_x000D_
_x000D_
input[type=range].range {_x000D_
    cursor: pointer;_x000D_
    width: 100px !important;_x000D_
    -webkit-appearance: none;_x000D_
    z-index: 200;_x000D_
    width: 50px;_x000D_
    border: 1px solid #e6e6e6;_x000D_
    background-color: #e6e6e6;_x000D_
    background-image: -webkit-gradient(linear, 0 0, 0 100%, from(#e6e6e6), to(#d2d2d2));_x000D_
    background-image: -webkit-linear-gradient(right, #e6e6e6, #d2d2d2);_x000D_
    background-image: -moz-linear-gradient(right, #e6e6e6, #d2d2d2);_x000D_
    background-image: -ms-linear-gradient(right, #e6e6e6, #d2d2d2);_x000D_
    background-image: -o-linear-gradient(right, #e6e6e6, #d2d2d2)_x000D_
}_x000D_
_x000D_
input[type=range].range:focus {_x000D_
    border: 0 !important;_x000D_
    outline: 0 !important_x000D_
}_x000D_
_x000D_
input[type=range].range::-webkit-slider-thumb {_x000D_
    -webkit-appearance: none;_x000D_
    width: 10px;_x000D_
    height: 10px;_x000D_
    background-color: #555;_x000D_
    background-image: -webkit-gradient(linear, 0 0, 0 100%, from(#4ddbff), to(#0cf));_x000D_
    background-image: -webkit-linear-gradient(right, #4ddbff, #0cf);_x000D_
    background-image: -moz-linear-gradient(right, #4ddbff, #0cf);_x000D_
    background-image: -ms-linear-gradient(right, #4ddbff, #0cf);_x000D_
    background-image: -o-linear-gradient(right, #4ddbff, #0cf)_x000D_
}_x000D_
_x000D_
input[type=range].round {_x000D_
    -webkit-border-radius: 20px;_x000D_
    -moz-border-radius: 20px;_x000D_
    border-radius: 20px_x000D_
}_x000D_
_x000D_
input[type=range].round::-webkit-slider-thumb {_x000D_
    -webkit-border-radius: 5px;_x000D_
    -moz-border-radius: 5px;_x000D_
    -o-border-radius: 5px_x000D_
}_x000D_
_x000D_
.vertical-lowest-first {_x000D_
    -webkit-transform: rotate(90deg);_x000D_
    -moz-transform: rotate(90deg);_x000D_
    -o-transform: rotate(90deg);_x000D_
    -ms-transform: rotate(90deg);_x000D_
    transform: rotate(90deg)_x000D_
}_x000D_
_x000D_
.vertical-heighest-first {_x000D_
    -webkit-transform: rotate(270deg);_x000D_
    -moz-transform: rotate(270deg);_x000D_
    -o-transform: rotate(270deg);_x000D_
    -ms-transform: rotate(270deg);_x000D_
    transform: rotate(270deg)_x000D_
}
_x000D_
<div class="container" style="margin-left: 0px">_x000D_
    <br><br>_x000D_
    <input class="range vertical-lowest-first" type="range" min="0" max="1" step="0.1" value="1">_x000D_
    <br><br><br>_x000D_
</div>_x000D_
_x000D_
<div class="container">_x000D_
    <br><br>_x000D_
    <input class="range vertical-heighest-first" type="range" min="0" max="1" step="0.1" value="1">_x000D_
    <br><br><br>_x000D_
</div>_x000D_
_x000D_
_x000D_
<div class="container">_x000D_
    <br><br>_x000D_
    <input class="range vertical-lowest-first round" type="range" min="0" max="1" step="0.1" value="1">_x000D_
    <br><br><br>_x000D_
</div>_x000D_
_x000D_
_x000D_
<div class="container" style="margin-right: 0px">_x000D_
    <br><br>_x000D_
    <input class="range vertical-heighest-first round" type="range" min="0" max="1" step="0.1" value="1">_x000D_
    <br><br><br>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Source: http://twiggle-web-design.com/tutorials/Custom-Vertical-Input-Range-CSS3.html

How do I install imagemagick with homebrew?

You could do:

brew reinstall php55-imagick

Where php55 is your PHP version.

Default Activity not found in Android Studio

When I clicked "Open Module Settings", there was no "Source" tab, I think because that's been removed for newer versions of Android Studio (I'm on 0.8.14). So I had to do this instead:

Add these lines to the build.gradle file inside the android { ... } block:

android { ... sourceSets { main.java.srcDirs += 'src/main/<YOUR DIRECTORY>' } }

After editing the file, click Tools > Android > Sync Project with Gradle Files.

Credit to this answer and this comment.

How to calculate age (in years) based on Date of Birth and getDate()

SELECT CAST(DATEDIFF(dy, @DOB, GETDATE()+1)/365.25 AS int)

About .bash_profile, .bashrc, and where should alias be written in?

The reason you separate the login and non-login shell is because the .bashrc file is reloaded every time you start a new copy of Bash. The .profile file is loaded only when you either log in or use the appropriate flag to tell Bash to act as a login shell.

Personally,

  • I put my PATH setup into a .profile file (because I sometimes use other shells);
  • I put my Bash aliases and functions into my .bashrc file;
  • I put this

    #!/bin/bash
    #
    # CRM .bash_profile Time-stamp: "2008-12-07 19:42"
    #
    # echo "Loading ${HOME}/.bash_profile"
    source ~/.profile # get my PATH setup
    source ~/.bashrc  # get my Bash aliases
    

    in my .bash_profile file.

Oh, and the reason you need to type bash again to get the new alias is that Bash loads your .bashrc file when it starts but it doesn't reload it unless you tell it to. You can reload the .bashrc file (and not need a second shell) by typing

source ~/.bashrc

which loads the .bashrc file as if you had typed the commands directly to Bash.

Are the days of passing const std::string & as a parameter over?

The problem is that "const" is a non-granular qualifier. What is usually meant by "const string ref" is "don't modify this string", not "don't modify the reference count". There is simply no way, in C++, to say which members are "const". They either all are, or none of them are.

In order to hack around this language issue, STL could allow "C()" in your example to make a move-semantic copy anyway, and dutifully ignore the "const" with regard to the reference count (mutable). As long as it was well-specified, this would be fine.

Since STL doesn't, I have a version of a string that const_casts<> away the reference counter (no way to retroactively make something mutable in a class hierarchy), and - lo and behold - you can freely pass cmstring's as const references, and make copies of them in deep functions, all day long, with no leaks or issues.

Since C++ offers no "derived class const granularity" here, writing up a good specification and making a shiny new "const movable string" (cmstring) object is the best solution I've seen.

Display an image with Python

Using Jupyter Notebook, the code can be as simple as the following.

%matplotlib inline
from IPython.display import Image
Image('your_image.png')

Sometimes you might would like to display a series of images in a for loop, in which case you might would like to combine display and Image to make it work.

%matplotlib inline
from IPython.display import display, Image
for your_image in your_images:
    display(Image('your_image'))

WPF Image Dynamically changing Image source during runtime

Hey, this one is kind of ugly but it's one line only:

imgTitle.Source = new BitmapImage(new Uri(@"pack://application:,,,/YourAssembly;component/your_image.png"));

How to generate keyboard events?

Every platform is going to have a different approach to being able to generate keyboard events. This is because they each need to make use of system libraries (and system extensions). For a cross platform solution, you would need to take each of these solutions and wrap then into a platform check to perform the proper approach.

For windows, you might be able to use the pywin32 extension. win32api.keybd_event

win32api.keybd_event

keybd_event(bVk, bScan, dwFlags, dwExtraInfo)

Simulate a keyboard event

Parameters

bVk : BYTE - Virtual-key code
bScan : BYTE - Hardware scan code
dwFlags=0 : DWORD - Flags specifying various function options
dwExtraInfo=0 : DWORD - Additional data associated with keystroke

You will need to investigate pywin32 for how to properly use it, as I have never used it.

Can jQuery read/write cookies to a browser?

A new jQuery plugin for cookie retrieval and manipulation with binding for forms, etc: http://plugins.jquery.com/project/cookies

Initializing data.frames()

I always just convert a matrix:

x <- as.data.frame(matrix(nrow = 100, ncol = 10))

'module' has no attribute 'urlencode'

import urllib.parse
urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})

How to programmatically move, copy and delete files and directories on SD?

Delete

public static void deleteRecursive(File fileOrDirectory) {

 if (fileOrDirectory.isDirectory())
    for (File child : fileOrDirectory.listFiles())
        deleteRecursive(child);

    fileOrDirectory.delete();

    }

check this link for above function.

Copy

public static void copyDirectoryOneLocationToAnotherLocation(File sourceLocation, File targetLocation)
    throws IOException {

if (sourceLocation.isDirectory()) {
    if (!targetLocation.exists()) {
        targetLocation.mkdir();
    }

    String[] children = sourceLocation.list();
    for (int i = 0; i < sourceLocation.listFiles().length; i++) {

        copyDirectoryOneLocationToAnotherLocation(new File(sourceLocation, children[i]),
                new File(targetLocation, children[i]));
    }
} else {

    InputStream in = new FileInputStream(sourceLocation);

    OutputStream out = new FileOutputStream(targetLocation);

    // Copy the bits from instream to outstream
    byte[] buf = new byte[1024];
    int len;
    while ((len = in.read(buf)) > 0) {
        out.write(buf, 0, len);
    }
    in.close();
    out.close();
}

}

Move

move is nothing just copy the folder one location to another then delete the folder thats it

manifest

     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Storing Data in MySQL as JSON

I would say the only two reasons to consider this are:

  • performance just isn't good enough with a normalised approach
  • you cannot readily model your particularly fluid/flexible/changing data

I wrote a bit about my own approach here:

What scalability problems have you encountered using a NoSQL data store?

(see the top answer)

Even JSON wasn't quite fast enough so we used a custom-text-format approach. Worked / continues to work well for us.

Is there a reason you're not using something like MongoDB? (could be MySQL is "required"; just curious)

Parallel foreach with asynchronous lambda

I've created an extension method for this which makes use of SemaphoreSlim and also allows to set maximum degree of parallelism

    /// <summary>
    /// Concurrently Executes async actions for each item of <see cref="IEnumerable<typeparamref name="T"/>
    /// </summary>
    /// <typeparam name="T">Type of IEnumerable</typeparam>
    /// <param name="enumerable">instance of <see cref="IEnumerable<typeparamref name="T"/>"/></param>
    /// <param name="action">an async <see cref="Action" /> to execute</param>
    /// <param name="maxDegreeOfParallelism">Optional, An integer that represents the maximum degree of parallelism,
    /// Must be grater than 0</param>
    /// <returns>A Task representing an async operation</returns>
    /// <exception cref="ArgumentOutOfRangeException">If the maxActionsToRunInParallel is less than 1</exception>
    public static async Task ForEachAsyncConcurrent<T>(
        this IEnumerable<T> enumerable,
        Func<T, Task> action,
        int? maxDegreeOfParallelism = null)
    {
        if (maxDegreeOfParallelism.HasValue)
        {
            using (var semaphoreSlim = new SemaphoreSlim(
                maxDegreeOfParallelism.Value, maxDegreeOfParallelism.Value))
            {
                var tasksWithThrottler = new List<Task>();

                foreach (var item in enumerable)
                {
                    // Increment the number of currently running tasks and wait if they are more than limit.
                    await semaphoreSlim.WaitAsync();

                    tasksWithThrottler.Add(Task.Run(async () =>
                    {
                        await action(item).ContinueWith(res =>
                        {
                            // action is completed, so decrement the number of currently running tasks
                            semaphoreSlim.Release();
                        });
                    }));
                }

                // Wait for all tasks to complete.
                await Task.WhenAll(tasksWithThrottler.ToArray());
            }
        }
        else
        {
            await Task.WhenAll(enumerable.Select(item => action(item)));
        }
    }

Sample Usage:

await enumerable.ForEachAsyncConcurrent(
    async item =>
    {
        await SomeAsyncMethod(item);
    },
    5);

Retrieving subfolders names in S3 bucket from boto3

It took me a lot of time to figure out, but finally here is a simple way to list contents of a subfolder in S3 bucket using boto3. Hope it helps

prefix = "folderone/foldertwo/"
s3 = boto3.resource('s3')
bucket = s3.Bucket(name="bucket_name_here")
FilesNotFound = True
for obj in bucket.objects.filter(Prefix=prefix):
     print('{0}:{1}'.format(bucket.name, obj.key))
     FilesNotFound = False
if FilesNotFound:
     print("ALERT", "No file in {0}/{1}".format(bucket, prefix))

sqlplus how to find details of the currently connected database session

select * from v$session
where sid = to_number(substr(dbms_session.unique_session_id,1,4),'XXXX')

creating list of objects in Javascript

Maybe you can create an array like this:

     var myList = new Array();
     myList.push('Hello');
     myList.push('bye');

     for (var i = 0; i < myList .length; i ++ ){
        window.console.log(myList[i]);
     }

"Could not find bundler" error

In my case I believe I had an old Ruby remaining on the system, not registered on rvm, and even if the path variables and gem list was okay, it would still use the old Ruby during deployments with Capistrano

And then I realized, the Ruby I had installed with rvm wasn't set to the default one. Running

rvm alias create default <rvm_registered_ruby>

Fixed it.

Python, creating objects

when you create an object using predefine class, at first you want to create a variable for storing that object. Then you can create object and store variable that you created.

class Student:
     def __init__(self):

# creating an object....

   student1=Student()

Actually this init method is the constructor of class.you can initialize that method using some attributes.. In that point , when you creating an object , you will have to pass some values for particular attributes..

class Student:
      def __init__(self,name,age):
            self.name=value
            self.age=value

 # creating an object.......

     student2=Student("smith",25)

cURL error 60: SSL certificate: unable to get local issuer certificate

Have you tried..

curl_setopt($process, CURLOPT_SSL_VERIFYPEER, false);

If you are consuming a trusted source you can skip the verify.

How to add multiple values to a dictionary key in python?

How about

a["abc"] = [1, 2]

This will result in:

>>> a
{'abc': [1, 2]}

Is that what you were looking for?

Converting characters to integers in Java

From the Javadoc for Character#getNumericValue:

If the character does not have a numeric value, then -1 is returned. If the character has a numeric value that cannot be represented as a nonnegative integer (for example, a fractional value), then -2 is returned.

The character + does not have a numeric value, so you're getting -1.

Update:

The reason that primitive conversion is giving you 43 is that the the character '+' is encoded as the integer 43.

How to get multiple selected values from select box in JSP?

Something along the lines of (using JSTL):

<p>Selected Values:
<ul>
  <c:forEach items="${paramValues['select2']}" var="selectedValue">
    <li><c:out value="${selectedValue}" /></li>
  </c:forEach>
</ul>
</p>

Return current date plus 7 days

you didn't use time() function that returns the current time measured in the number of seconds since the Unix Epoch (January 1 1970 00:00:00 GMT). use like this:

$date = strtotime(time());
$date = strtotime("+7 day", $date);
echo date('M d, Y', $date);

How can I add private key to the distribution certificate?

For Developer certificate, you need to create a developer .mobileprovision profile and install add it to your XCode. In case you want to distribute the app using an adhoc distribution profile you will require AdHoc Distribution certificate and private key installed in your keychain.

If you have not created the cert, here are steps to create it. Incase it has already been created by someone in your team, ask him to share the cert and private key. If that someone is no longer in your team then you can revoke the cert from developer account and create new.

Getting "conflicting types for function" in C, why?

When you don't give a prototype for the function before using it, C assumes that it takes any number of parameters and returns an int. So when you first try to use do_something, that's the type of function the compiler is looking for. Doing this should produce a warning about an "implicit function declaration".

So in your case, when you actually do declare the function later on, C doesn't allow function overloading, so it gets pissy because to it you've declared two functions with different prototypes but with the same name.

Short answer: declare the function before trying to use it.

Android getText from EditText field

Try out this will solve ur problem ....

EditText etxt = (EditText)findviewbyid(R.id.etxt);
String str_value = etxt.getText().toString();

Move top 1000 lines from text file to a new file using Unix shell commands

Out of curiosity, I found a box with a GNU version of sed (v4.1.5) and tested the (uncached) performance of two approaches suggested so far, using an 11M line text file:

$ wc -l input
11771722 input

$ time head -1000 input > output; time tail -n +1000 input > input.tmp; time cp input.tmp input; time rm input.tmp

real    0m1.165s
user    0m0.030s
sys     0m1.130s

real    0m1.256s
user    0m0.062s
sys     0m1.162s

real    0m4.433s
user    0m0.033s
sys     0m1.282s

real    0m6.897s
user    0m0.000s
sys     0m0.159s

$ time head -1000 input > output && time sed -i '1,+999d' input

real    0m0.121s
user    0m0.000s
sys     0m0.121s

real    0m26.944s
user    0m0.227s
sys     0m26.624s

This is the Linux I was working with:

$ uname -a
Linux hostname 2.6.18-128.1.1.el5 #1 SMP Mon Jan 26 13:58:24 EST 2009 x86_64 x86_64 x86_64 GNU/Linux

For this test, at least, it looks like sed is slower than the tail approach (27 sec vs ~14 sec).

an htop-like tool to display disk activity in linux

It is not htop-like, but you could use atop. However, to display disk activity per process, it needs a kernel patch (available from the site). These kernel patches are now obsoleted, only to show per-process network activity an optional module is provided.

Microsoft.WebApplication.targets was not found, on the build server. What's your solution?

You can also use the NuGet package MSBuild.Microsoft.VisualStudio.Web.targets, referencing them within your Visual Studio project(s), then change your references as Andriy K suggests.

Getting attributes of Enum's value

I've merged a couple of the answers here to create a little more extensible solution. I'm providing it just in case it's helpful to anyone else in the future. Original posting here.

using System;
using System.ComponentModel;

public static class EnumExtensions {

    // This extension method is broken out so you can use a similar pattern with 
    // other MetaData elements in the future. This is your base method for each.
    public static T GetAttribute<T>(this Enum value) where T : Attribute {
        var type = value.GetType();
        var memberInfo = type.GetMember(value.ToString());
        var attributes = memberInfo[0].GetCustomAttributes(typeof(T), false);
        return attributes.Length > 0 
          ? (T)attributes[0]
          : null;
    }

    // This method creates a specific call to the above method, requesting the
    // Description MetaData attribute.
    public static string ToName(this Enum value) {
        var attribute = value.GetAttribute<DescriptionAttribute>();
        return attribute == null ? value.ToString() : attribute.Description;
    }

}

This solution creates a pair of extension methods on Enum. The first allows you to use reflection to retrieve any attribute associated with your value. The second specifically calls retrieves the DescriptionAttribute and returns it's Description value.

As an example, consider using the DescriptionAttribute attribute from System.ComponentModel

using System.ComponentModel;

public enum Days {
    [Description("Sunday")]
    Sun,
    [Description("Monday")]
    Mon,
    [Description("Tuesday")]
    Tue,
    [Description("Wednesday")]
    Wed,
    [Description("Thursday")]
    Thu,
    [Description("Friday")]
    Fri,
    [Description("Saturday")]
    Sat
}

To use the above extension method, you would now simply call the following:

Console.WriteLine(Days.Mon.ToName());

or

var day = Days.Mon;
Console.WriteLine(day.ToName());

Why does one use dependency injection?

First, I want to explain an assumption that I make for this answer. It is not always true, but quite often:

Interfaces are adjectives; classes are nouns.

(Actually, there are interfaces that are nouns as well, but I want to generalize here.)

So, e.g. an interface may be something such as IDisposable, IEnumerable or IPrintable. A class is an actual implementation of one or more of these interfaces: List or Map may both be implementations of IEnumerable.

To get the point: Often your classes depend on each other. E.g. you could have a Database class which accesses your database (hah, surprise! ;-)), but you also want this class to do logging about accessing the database. Suppose you have another class Logger, then Database has a dependency to Logger.

So far, so good.

You can model this dependency inside your Database class with the following line:

var logger = new Logger();

and everything is fine. It is fine up to the day when you realize that you need a bunch of loggers: Sometimes you want to log to the console, sometimes to the file system, sometimes using TCP/IP and a remote logging server, and so on ...

And of course you do NOT want to change all your code (meanwhile you have gazillions of it) and replace all lines

var logger = new Logger();

by:

var logger = new TcpLogger();

First, this is no fun. Second, this is error-prone. Third, this is stupid, repetitive work for a trained monkey. So what do you do?

Obviously it's a quite good idea to introduce an interface ICanLog (or similar) that is implemented by all the various loggers. So step 1 in your code is that you do:

ICanLog logger = new Logger();

Now the type inference doesn't change type any more, you always have one single interface to develop against. The next step is that you do not want to have new Logger() over and over again. So you put the reliability to create new instances to a single, central factory class, and you get code such as:

ICanLog logger = LoggerFactory.Create();

The factory itself decides what kind of logger to create. Your code doesn't care any longer, and if you want to change the type of logger being used, you change it once: Inside the factory.

Now, of course, you can generalize this factory, and make it work for any type:

ICanLog logger = TypeFactory.Create<ICanLog>();

Somewhere this TypeFactory needs configuration data which actual class to instantiate when a specific interface type is requested, so you need a mapping. Of course you can do this mapping inside your code, but then a type change means recompiling. But you could also put this mapping inside an XML file, e.g.. This allows you to change the actually used class even after compile time (!), that means dynamically, without recompiling!

To give you a useful example for this: Think of a software that does not log normally, but when your customer calls and asks for help because he has a problem, all you send to him is an updated XML config file, and now he has logging enabled, and your support can use the log files to help your customer.

And now, when you replace names a little bit, you end up with a simple implementation of a Service Locator, which is one of two patterns for Inversion of Control (since you invert control over who decides what exact class to instantiate).

All in all this reduces dependencies in your code, but now all your code has a dependency to the central, single service locator.

Dependency injection is now the next step in this line: Just get rid of this single dependency to the service locator: Instead of various classes asking the service locator for an implementation for a specific interface, you - once again - revert control over who instantiates what.

With dependency injection, your Database class now has a constructor that requires a parameter of type ICanLog:

public Database(ICanLog logger) { ... }

Now your database always has a logger to use, but it does not know any more where this logger comes from.

And this is where a DI framework comes into play: You configure your mappings once again, and then ask your DI framework to instantiate your application for you. As the Application class requires an ICanPersistData implementation, an instance of Database is injected - but for that it must first create an instance of the kind of logger which is configured for ICanLog. And so on ...

So, to cut a long story short: Dependency injection is one of two ways of how to remove dependencies in your code. It is very useful for configuration changes after compile-time, and it is a great thing for unit testing (as it makes it very easy to inject stubs and / or mocks).

In practice, there are things you can not do without a service locator (e.g., if you do not know in advance how many instances you do need of a specific interface: A DI framework always injects only one instance per parameter, but you can call a service locator inside a loop, of course), hence most often each DI framework also provides a service locator.

But basically, that's it.

P.S.: What I described here is a technique called constructor injection, there is also property injection where not constructor parameters, but properties are being used for defining and resolving dependencies. Think of property injection as an optional dependency, and of constructor injection as mandatory dependencies. But discussion on this is beyond the scope of this question.

java.lang.ClassCastException

ClassA a = <something>;
ClassB b = (ClassB) a;

The 2nd line will fail if ClassA is not a subclass of ClassB, and will throw a ClassCastException.

Bootstrap $('#myModal').modal('show') is not working

<div class="modal fade" id="myModal" aria-hidden="true">
   ...
   ...
</div>

Note: Remove fade class from the div and enjoy it should be worked

PL/SQL, how to escape single quote in a string?

You can use literal quoting:

stmt := q'[insert into MY_TBL (Col) values('ER0002')]';

Documentation for literals can be found here.

Alternatively, you can use two quotes to denote a single quote:

stmt := 'insert into MY_TBL (Col) values(''ER0002'')';

The literal quoting mechanism with the Q syntax is more flexible and readable, IMO.

Python get current time in right timezone

To get the current time in the local timezone as a naive datetime object:

from datetime import datetime
naive_dt = datetime.now()

If it doesn't return the expected time then it means that your computer is misconfigured. You should fix it first (it is unrelated to Python).

To get the current time in UTC as a naive datetime object:

naive_utc_dt = datetime.utcnow()

To get the current time as an aware datetime object in Python 3.3+:

from datetime import datetime, timezone

utc_dt = datetime.now(timezone.utc) # UTC time
dt = utc_dt.astimezone() # local time

To get the current time in the given time zone from the tz database:

import pytz

tz = pytz.timezone('Europe/Berlin')
berlin_now = datetime.now(tz)

It works during DST transitions. It works if the timezone had different UTC offset in the past i.e., it works even if the timezone corresponds to multiple tzinfo objects at different times.

Git - fatal: Unable to create '/path/my_project/.git/index.lock': File exists

The resolution for this problem is copying the three xcode/project files in the directory and then creating new directory (Whereever else) and then paste the three files/directories.

Can Json.NET serialize / deserialize to / from a stream?

UPDATE: This no longer works in the current version, see below for correct answer (no need to vote down, this is correct on older versions).

Use the JsonTextReader class with a StreamReader or use the JsonSerializer overload that takes a StreamReader directly:

var serializer = new JsonSerializer();
serializer.Deserialize(streamReader);

What exceptions should be thrown for invalid or unexpected parameters in .NET?

ArgumentException:

ArgumentException is thrown when a method is invoked and at least one of the passed arguments does not meet the parameter specification of the called method. All instances of ArgumentException should carry a meaningful error message describing the invalid argument, as well as the expected range of values for the argument.

A few subclasses also exist for specific types of invalidity. The link has summaries of the subtypes and when they should apply.

Multiple Order By with LINQ

You can use the ThenBy and ThenByDescending extension methods:

foobarList.OrderBy(x => x.Foo).ThenBy( x => x.Bar)

SQL DROP TABLE foreign key constraint

No, this will not drop your table if there are indeed foreign keys referencing it.

To get all foreign key relationships referencing your table, you could use this SQL (if you're on SQL Server 2005 and up):

SELECT * 
FROM sys.foreign_keys
WHERE referenced_object_id = object_id('Student')

and if there are any, with this statement here, you could create SQL statements to actually drop those FK relations:

SELECT 
    'ALTER TABLE [' +  OBJECT_SCHEMA_NAME(parent_object_id) +
    '].[' + OBJECT_NAME(parent_object_id) + 
    '] DROP CONSTRAINT [' + name + ']'
FROM sys.foreign_keys
WHERE referenced_object_id = object_id('Student')

How to write subquery inside the OUTER JOIN Statement

You need the "correlation id" (the "AS SS" thingy) on the sub-select to reference the fields in the "ON" condition. The id's assigned inside the sub select are not usable in the join.

SELECT
       cs.CUSID
       ,dp.DEPID
FROM
    CUSTMR cs
        LEFT OUTER JOIN (
            SELECT
                    DEPID
                    ,DEPNAME
                FROM
                    DEPRMNT 
                WHERE
                    dp.DEPADDRESS = 'TOKYO'
        ) ss
            ON (
                ss.DEPID = cs.CUSID
                AND ss.DEPNAME = cs.CUSTNAME
            )
WHERE
    cs.CUSID != '' 

Address already in use: JVM_Bind

The logged error does say that port 3820 is the problem, but I would suggest investigating all the ports that your app is trying to listen on. I ran into this problem and the issue was a port that I'd forgotten about - not the "main" one that I was looking for.

How to file split at a line number

file_name=test.log

# set first K lines:
K=1000

# line count (N): 
N=$(wc -l < $file_name)

# length of the bottom file:
L=$(( $N - $K ))

# create the top of file: 
head -n $K $file_name > top_$file_name

# create bottom of file: 
tail -n $L $file_name > bottom_$file_name

Also, on second thought, split will work in your case, since the first split is larger than the second. Split puts the balance of the input into the last split, so

split -l 300000 file_name

will output xaa with 300k lines and xab with 100k lines, for an input with 400k lines.

Difference between text and varchar (character varying)

As "Character Types" in the documentation points out, varchar(n), char(n), and text are all stored the same way. The only difference is extra cycles are needed to check the length, if one is given, and the extra space and time required if padding is needed for char(n).

However, when you only need to store a single character, there is a slight performance advantage to using the special type "char" (keep the double-quotes — they're part of the type name). You get faster access to the field, and there is no overhead to store the length.

I just made a table of 1,000,000 random "char" chosen from the lower-case alphabet. A query to get a frequency distribution (select count(*), field ... group by field) takes about 650 milliseconds, vs about 760 on the same data using a text field.

CSS3 100vh not constant in mobile browser

You can try giving position: fixed; top: 0; bottom: 0; properties to your container.

How to make a Div appear on top of everything else on the screen?

Set the DIV's z-index to one larger than the other DIVs. You'll also need to make sure the DIV has a position other than static set on it, too.

CSS:

#someDiv {
    z-index:9; 
}

Read more here: http://coding.smashingmagazine.com/2009/09/15/the-z-index-css-property-a-comprehensive-look/

Select Multiple Fields from List in Linq

var result = listObject.Select( i => new{ i.category_name, i.category_id } )

This uses anonymous types so you must the var keyword, since the resulting type of the expression is not known in advance.

How do I get the real .height() of a overflow: hidden or overflow: scroll div?

For more information about .scrollHeight property refer to the docs:

The Element.scrollHeight read-only attribute is a measurement of the height of an element's content, including content not visible on the screen due to overflow. The scrollHeight value is equal to the minimum clientHeight the element would require in order to fit all the content in the viewpoint without using a vertical scrollbar. It includes the element padding but not its margin.

Why Is `Export Default Const` invalid?

You can also do something like this if you want to export default a const/let, instead of

const MyComponent = ({ attr1, attr2 }) => (<p>Now Export On other Line</p>);
export default MyComponent

You can do something like this, which I do not like personally.

let MyComponent;
export default MyComponent = ({ }) => (<p>Now Export On SameLine</p>);

How to export a table dataframe in PySpark to csv?

If you cannot use spark-csv, you can do the following:

df.rdd.map(lambda x: ",".join(map(str, x))).coalesce(1).saveAsTextFile("file.csv")

If you need to handle strings with linebreaks or comma that will not work. Use this:

import csv
import cStringIO

def row2csv(row):
    buffer = cStringIO.StringIO()
    writer = csv.writer(buffer)
    writer.writerow([str(s).encode("utf-8") for s in row])
    buffer.seek(0)
    return buffer.read().strip()

df.rdd.map(row2csv).coalesce(1).saveAsTextFile("file.csv")

How to count the number of rows in excel with data?

These would both work as well, letting Excel define the last time it sees data

numofrows = destsheet.UsedRange.SpecialCells(xlLastCell).row

numofrows = destsheet.Cells.SpecialCells(xlLastCell).row

Radio buttons not checked in jQuery

If my firebug profiler work fine (and i know how to use it well), this:

$('#communitymode').attr('checked')

is faster than

$('#communitymode').is('checked')

You can try on this page :)

And then you can use it like

if($('#communitymode').attr('checked')===true) { 
// do something
}

Maven dependencies are failing with a 501 error

The following link got me out of the trouble,

https://support.sonatype.com/hc/en-us/articles/360041287334-Central-501-HTTPS-Required

You could make the changes either in your maven, apache-maven/conf/settings.xml. Or, if you are specifying in your pom.xml, make the change there.

Before,

<repository>
            <id>maven_central_repo</id>
            <url>http://repo.maven.apache.org/maven2</url>
</repository>

Now,

<repository>
            <id>maven_central_repo</id>
            <url>https://repo.maven.apache.org/maven2</url>
</repository>

JS strings "+" vs concat method

You can try with this code (Same case)

chaine1 + chaine2; 

I suggest you also (I prefer this) the string.concat method

How to open Emacs inside Bash

Try emacs —daemon to have Emacs running in the background, and emacsclient to connect to the Emacs server.

It’s not much time overhead saved on modern systems, but it’s a lot better than running several instances of Emacs.

Bi-directional Map in Java?

There is no bidirectional map in the Java Standard API. Either you can maintain two maps yourself or use the BidiMap from Apache Collections.

Matplotlib: Specify format of floats for tick labels

The answer above is probably the correct way to do it, but didn't work for me.

The hacky way that solved it for me was the following:

ax = <whatever your plot is> 
# get the current labels 
labels = [item.get_text() for item in ax.get_xticklabels()]
# Beat them into submission and set them back again
ax.set_xticklabels([str(round(float(label), 2)) for label in labels])
# Show the plot, and go home to family 
plt.show()

What does this square bracket and parenthesis bracket notation mean [first1,last1)?

It can be a mathematical convention in the definition of an interval where square brackets mean "extremal inclusive" and round brackets "extremal exclusive".

Msg 102, Level 15, State 1, Line 1 Incorrect syntax near ' '

For the OP's command:

select compid,2, convert(datetime, '01/01/' + CONVERT(char(4),cal_yr) ,101) ,0,  Update_dt, th1, th2, th3_pc , Update_id, Update_dt,1
from  #tmp_CTF** 

I get this error:

Msg 102, Level 15, State 1, Line 2
Incorrect syntax near '*'.

when debugging something like this split the long line up so you'll get a better row number:

select compid
,2
, convert(datetime
, '01/01/' 
+ CONVERT(char(4)
,cal_yr) 
,101) 
,0
,  Update_dt
, th1
, th2
, th3_pc 
, Update_id
, Update_dt
,1
from  #tmp_CTF** 

this now results in:

Msg 102, Level 15, State 1, Line 16
Incorrect syntax near '*'.

which is probably just from the OP not putting the entire command in the question, or use [ ] braces to signify the table name:

from [#tmp_CTF**]

if that is the table name.

Trying to embed newline in a variable in bash

there is no need to use for cycle

you can benefit from bash parameter expansion functions:

var="a b c"; 
var=${var// /\\n}; 
echo -e $var
a
b
c

or just use tr:

var="a b c"
echo $var | tr " " "\n"
a
b
c

Error: Unfortunately you can't have non-Gradle Java modules and > Android-Gradle modules in one project

This solution worked for me Android Studio 3.3.2.

  1. Delete the .iml file from the project directory.
  2. In android studio File->invalidate caches/restart.
  3. Clean and Rebuild project if the auto build throws error.

Matching a Forward Slash with a regex

For me, I was trying to match on the / in a date in C#. I did it just by using (\/):

string pattern = "([0-9])([0-9])?(\/)([0-9])([0-9])?(\/)(\d{4})";
string text = "Start Date: 4/1/2018";

Match m = Regex.Match(text, pattern);

if (m.Success) 
{ 
    Console.WriteLine(match.Groups[0].Value);  // 4/1/2018
}
else
{
    Console.WriteLine("Not Found!");
}

JavaScript should also be able to similarly use (\/).

CSS Background Opacity

Children inherit opacity. It'd be weird and inconvenient if they didn't.

You can use a translucent PNG file for your background image, or use an RGBa (a for alpha) color for your background color.

Example, 50% faded black background:

_x000D_
_x000D_
<div style="background-color:rgba(0, 0, 0, 0.5);">_x000D_
   <div>_x000D_
      Text added._x000D_
   </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

CSS border less than 1px

try giving border in % for exapmle 0.1% according to your need.

How to place two divs next to each other?

Try to use below code changes to place two divs in front of each other

#wrapper {
  width: 500px;
  border: 1px solid black;
  display:flex;
}

JSFiddle link

Set default time in bootstrap-datetimepicker

Momentjs.com has good documentation on how to manipulate the date/time in relation to the current moment. Since Momentjs is required for the Datetimepicker, might as well use it.

var startDefault = moment().startof('day').add(1, 'minutes');
$('#startdatetime-from').datetimepicker({
    defaultDate: startDefault,
    language: 'en',
    format: 'yyyy-MM-dd hh:mm'
});

HTML5 video won't play in Chrome only

I had a similar issue, no videos would play in Chrome. Tried installing beta 64bit, going back to Chrome 32bit release.

The only thing that worked for me was updating my video drivers.

I have the NVIDIA GTS 240. Downloaded, installed the drivers and restarted and Chrome 38.0.2125.77 beta-m (64-bit) starting playing HTML5 videos again on youtube, vimeo and others. Hope this helps anyone else.

How to use execvp()

The first argument is the file you wish to execute, and the second argument is an array of null-terminated strings that represent the appropriate arguments to the file as specified in the man page.

For example:

char *cmd = "ls";
char *argv[3];
argv[0] = "ls";
argv[1] = "-la";
argv[2] = NULL;

execvp(cmd, argv); //This will run "ls -la" as if it were a command

How do I put the image on the right side of the text in a UIButton?

Extension Way

Using extension to set image on the right side with custom offset

   extension UIButton {
    func addRightImage(image: UIImage, offset: CGFloat) {
        self.setImage(image, for: .normal)
        self.imageView?.translatesAutoresizingMaskIntoConstraints = false
        self.imageView?.centerYAnchor.constraint(equalTo: self.centerYAnchor, constant: 0.0).isActive = true
        self.imageView?.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: -offset).isActive = true
    }
}

I want to get the type of a variable at runtime

If by the type of a variable you mean the runtime class of the object that the variable points to, then you can get this through the class reference that all objects have.

val name = "sam";
name: java.lang.String = sam
name.getClass
res0: java.lang.Class[_] = class java.lang.String

If you however mean the type that the variable was declared as, then you cannot get that. Eg, if you say

val name: Object = "sam"

then you will still get a String back from the above code.

Find the greatest number in a list of numbers

What about max()

highest = max(1, 2, 3)  # or max([1, 2, 3]) for lists

How to convert Set<String> to String[]?

Use toArray(T[] a) method:

String[] array = set.toArray(new String[0]);

Add Items to ListView - Android

public OnClickListener moreListener = new OnClickListener() {

    @Override
      public void onClick(View v) {
          adapter.add("aaaa")
      }
}

RuntimeWarning: invalid value encountered in divide

You are dividing by rr which may be 0.0. Check if rr is zero and do something reasonable other than using it in the denominator.

How to make div appear in front of another?

In order an element to appear in front of another you have to give higher z-index to the front element, and lower z-index to the back element, also you should indicate position: absolute/fixed...

Example:

<div style="z-index:100; position: fixed;">Hello</div>
<div style="z-index: -1;">World</div>

Why does Math.Round(2.5) return 2 instead of 3?

I had this problem where my SQL server rounds up 0.5 to 1 while my C# application didn't. So you would see two different results.

Here's an implementation with int/long. This is how Java rounds.

int roundedNumber = (int)Math.Floor(d + 0.5);

It's probably the most efficient method you could think of as well.

If you want to keep it a double and use decimal precision , then it's really just a matter of using exponents of 10 based on how many decimal places.

public double getRounding(double number, int decimalPoints)
{
    double decimalPowerOfTen = Math.Pow(10, decimalPoints);
    return Math.Floor(number * decimalPowerOfTen + 0.5)/ decimalPowerOfTen;
}

You can input a negative decimal for decimal points and it's word fine as well.

getRounding(239, -2) = 200

Python safe method to get value of nested dictionary

def safeget(_dct, *_keys):
    if not isinstance(_dct, dict): raise TypeError("Is not instance of dict")
    def foo(dct, *keys):
        if len(keys) == 0: return dct
        elif not isinstance(_dct, dict): return None
        else: return foo(dct.get(keys[0], None), *keys[1:])
    return foo(_dct, *_keys)

assert safeget(dict()) == dict()
assert safeget(dict(), "test") == None
assert safeget(dict([["a", 1],["b", 2]]),"a", "d") == None
assert safeget(dict([["a", 1],["b", 2]]),"a") == 1
assert safeget({"a":{"b":{"c": 2}},"d":1}, "a", "b")["c"] == 2

How to run a C# console application with the console hidden

If you're interested in the output, you can use this function:

private static string ExecCommand(string filename, string arguments)
{
    Process process = new Process();
    ProcessStartInfo psi = new ProcessStartInfo(filename);
    psi.Arguments = arguments;
    psi.CreateNoWindow = true;
    psi.RedirectStandardOutput = true;
    psi.RedirectStandardError = true;
    psi.UseShellExecute = false;
    process.StartInfo = psi;

    StringBuilder output = new StringBuilder();
    process.OutputDataReceived += (sender, e) => { output.AppendLine(e.Data); };
    process.ErrorDataReceived += (sender, e) => { output.AppendLine(e.Data); };

    // run the process
    process.Start();

    // start reading output to events
    process.BeginOutputReadLine();
    process.BeginErrorReadLine();

    // wait for process to exit
    process.WaitForExit();

    if (process.ExitCode != 0)
        throw new Exception("Command " + psi.FileName + " returned exit code " + process.ExitCode);

    return output.ToString();
}

It runs the given command line program, waits for it to finish and returns the output as string.

Allow docker container to connect to a local/host postgres database

The solution posted here does not work for me. Therefore, I am posting this answer to help someone facing similar issue.

OS: Ubuntu 18
PostgreSQL: 9.5 (Hosted on Ubuntu)
Docker: Server Application (which connects to PostgreSQL)

I am using docker-compose.yml to build application.

STEP 1: Please add host.docker.internal:<docker0 IP>

version: '3'
services:
  bank-server:
    ...
    depends_on:
      ....
    restart: on-failure
    ports:
      - 9090:9090
    extra_hosts:
      - "host.docker.internal:172.17.0.1"

To find IP of docker i.e. 172.17.0.1 (in my case) you can use:

$> ifconfig docker0
docker0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 172.17.0.1  netmask 255.255.0.0  broadcast 172.17.255.255

OR

$> ip a
1: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever

STEP 2: In postgresql.conf, change listen_addresses to listen_addresses = '*'

STEP 3: In pg_hba.conf, add this line

host    all             all             0.0.0.0/0               md5

STEP 4: Now restart postgresql service using, sudo service postgresql restart

STEP 5: Please use host.docker.internal hostname to connect database from Server Application.
Ex: jdbc:postgresql://host.docker.internal:5432/bankDB

Enjoy!!

How to implement my very own URI scheme on Android

Another alternate approach to Diego's is to use a library:

https://github.com/airbnb/DeepLinkDispatch

You can easily declare the URIs you'd like to handle and the parameters you'd like to extract through annotations on the Activity, like:

@DeepLink("path/to/what/i/want")
public class SomeActivity extends Activity {
  ...
}

As a plus, the query parameters will also be passed along to the Activity as well.

Error: " 'dict' object has no attribute 'iteritems' "

I had a similar problem (using 3.5) and lost 1/2 a day to it but here is a something that works - I am retired and just learning Python so I can help my grandson (12) with it.

mydict2={'Atlanta':78,'Macon':85,'Savannah':72}
maxval=(max(mydict2.values()))
print(maxval)
mykey=[key for key,value in mydict2.items()if value==maxval][0]
print(mykey)
YEILDS; 
85
Macon

git pull keeping local changes

Incase their is local uncommitted changes and avoid merge conflict while pulling.

git stash save
git pull
git stash pop

refer - https://happygitwithr.com/pull-tricky.html

How can I calculate the number of years between two dates?

function getYearDiff(startDate, endDate) {
    let yearDiff = endDate.getFullYear() - startDate.getFullYear();
    if (startDate.getMonth() > endDate.getMonth()) {
        yearDiff--;
    } else if (startDate.getMonth() === endDate.getMonth()) {
        if (startDate.getDate() > endDate.getDate()) {
            yearDiff--;
        } else if (startDate.getDate() === endDate.getDate()) {
            if (startDate.getHours() > endDate.getHours()) {
                yearDiff--;
            } else if (startDate.getHours() === endDate.getHours()) {
                if (startDate.getMinutes() > endDate.getMinutes()) {
                    yearDiff--;
                }
            }
        }
    }
    return yearDiff;
}

alert(getYearDiff(firstDate, secondDate));

JTable How to refresh table model after insert delete or update the data.

try this

public void setUpTableData() {
    DefaultTableModel tableModel = (DefaultTableModel) jTable.getModel();

    /**
    * additional code.
    **/
    tableModel.setRowCount(0);
    /**/
    ArrayList<Contact> list = new ArrayList<Contact>();
    if (!con.equals(""))
        list = sql.getContactListsByGroup(con);
    else
        list = sql.getContactLists();
    for (int i = 0; i < list.size(); i++) {
        String[] data = new String[7];

        data[0] = list.get(i).getName();
        data[1] = list.get(i).getEmail();
        data[2] = list.get(i).getPhone1();
        data[3] = list.get(i).getPhone2();
        data[4] = list.get(i).getGroup();
        data[5] = list.get(i).getId();

        tableModel.addRow(data);
    }
    jTable.setModel(tableModel);
    /**
    * additional code.
    **/
    tableModel.fireTableDataChanged();
    /**/
}

How to make div's percentage width relative to parent div and not viewport

Specifying a non-static position, e.g., position: absolute/relative on a node means that it will be used as the reference for absolutely positioned elements within it http://jsfiddle.net/E5eEk/1/

See https://developer.mozilla.org/en-US/docs/Learn/CSS/CSS_layout/Positioning#Positioning_contexts

We can change the positioning context — which element the absolutely positioned element is positioned relative to. This is done by setting positioning on one of the element's ancestors.

_x000D_
_x000D_
#outer {_x000D_
  min-width: 2000px; _x000D_
  min-height: 1000px; _x000D_
  background: #3e3e3e; _x000D_
  position:relative_x000D_
}_x000D_
_x000D_
#inner {_x000D_
  left: 1%; _x000D_
  top: 45px; _x000D_
  width: 50%; _x000D_
  height: auto; _x000D_
  position: absolute; _x000D_
  z-index: 1;_x000D_
}_x000D_
_x000D_
#inner-inner {_x000D_
  background: #efffef;_x000D_
  position: absolute; _x000D_
  height: 400px; _x000D_
  right: 0px; _x000D_
  left: 0px;_x000D_
}
_x000D_
<div id="outer">_x000D_
  <div id="inner">_x000D_
    <div id="inner-inner"></div>_x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Broadcast receiver for checking internet connection in android app

manifest:

<receiver android:name=".your.namepackage.here.ConnectivityReceiver">
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
    </intent-filter>
</receiver>

class for receiver:

public class ConnectivityReceiver extends BroadcastReceiver{

    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();
        switch (action) {
            case ConnectivityManager.CONNECTIVITY_ACTION:
                DebugUtils.logDebug("BROADCAST", "network change");
                if(NetworkUtils.isConnect()){
                    //do action here
                }
            break;
        }
    }
}

and classs utils like example:

public class NetworkUtils {

    public static boolean isConnect() {
        ConnectivityManager connectivityManager = (ConnectivityManager) Application.getInstance().getSystemService(Context.CONNECTIVITY_SERVICE);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            Network[] netArray = connectivityManager.getAllNetworks();
            NetworkInfo netInfo;
            for (Network net : netArray) {
                netInfo = connectivityManager.getNetworkInfo(net);
                if ((netInfo.getTypeName().equalsIgnoreCase("WIFI") || netInfo.getTypeName().equalsIgnoreCase("MOBILE")) && netInfo.isConnected() && netInfo.isAvailable()) {
                    //if (netInfo.getState().equals(NetworkInfo.State.CONNECTED)) {
                    Log.d("Network", "NETWORKNAME: " + netInfo.getTypeName());
                    return true;
                }
            }
        } else {
            if (connectivityManager != null) {
                @SuppressWarnings("deprecation")
                NetworkInfo[] netInfoArray = connectivityManager.getAllNetworkInfo();
                if (netInfoArray != null) {
                    for (NetworkInfo netInfo : netInfoArray) {
                        if ((netInfo.getTypeName().equalsIgnoreCase("WIFI") || netInfo.getTypeName().equalsIgnoreCase("MOBILE")) && netInfo.isConnected() && netInfo.isAvailable()) {
                            //if (netInfo.getState() == NetworkInfo.State.CONNECTED) {
                            Log.d("Network", "NETWORKNAME: " + netInfo.getTypeName());
                            return true;
                        }
                    }
                }
            }
        }
        return false;
    }
}

How to Change Font Size in drawString Java

code example below:

g.setFont(new Font("TimesRoman", Font.PLAIN, 30));
g.drawString("Welcome to the Java Applet", 20 , 20);

What's the scope of a variable initialized in an if statement?

As Eli said, Python doesn't require variable declaration. In C you would say:

int x;
if(something)
    x = 1;
else
    x = 2;

but in Python declaration is implicit, so when you assign to x it is automatically declared. It's because Python is dynamically typed - it wouldn't work in a statically typed language, because depending on the path used, a variable might be used without being declared. This would be caught at compile time in a statically typed language, but with a dynamically typed language it's allowed.

The only reason that a statically typed language is limited to having to declare variables outside of if statements in because of this problem. Embrace the dynamic!

How to send Request payload to REST API in java?

The following code works for me.

//escape the double quotes in json string
String payload="{\"jsonrpc\":\"2.0\",\"method\":\"changeDetail\",\"params\":[{\"id\":11376}],\"id\":2}";
String requestUrl="https://git.eclipse.org/r/gerrit/rpc/ChangeDetailService";
sendPostRequest(requestUrl, payload);

method implementation:

public static String sendPostRequest(String requestUrl, String payload) {
    try {
        URL url = new URL(requestUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Accept", "application/json");
        connection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
        OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
        writer.write(payload);
        writer.close();
        BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        StringBuffer jsonString = new StringBuffer();
        String line;
        while ((line = br.readLine()) != null) {
                jsonString.append(line);
        }
        br.close();
        connection.disconnect();
        return jsonString.toString();
    } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
    }

}

Adding double quote delimiters into csv file

This is actually pretty easy in Excel (or any spreadsheet application).

You'll want to use the =CONCATENATE() function as shown in the formula bar in the following screenshot:

Step 1 involves adding quotes in column B,

Step 2 involves specifying the function and then copying it down column C (by now your spreadsheet should look like the screenshot),

enter image description here

Step 3 (if you need the text outside of the formula) involves copying column C, right-clicking on column D, choosing Paste Special >> Paste Values. Column D should then contain the text that was calculated in column C.

LAST_INSERT_ID() MySQL

You could store the last insert id in a variable :

INSERT INTO table1 (title,userid) VALUES ('test', 1); 
SET @last_id_in_table1 = LAST_INSERT_ID();
INSERT INTO table2 (parentid,otherid,userid) VALUES (@last_id_in_table1, 4, 1);    

Or get the max id frm table1

INSERT INTO table1 (title,userid) VALUES ('test', 1); 
INSERT INTO table2 (parentid,otherid,userid) VALUES (LAST_INSERT_ID(), 4, 1); 
SELECT MAX(id) FROM table1;   

Counting Line Numbers in Eclipse

Here's a good metrics plugin that displays number of lines of code and much more:

http://metrics.sourceforge.net/

It says it requires Eclipse 3.1, although I imagine they mean 3.1+

Here's another metrics plugin that's been tested on Ganymede:

http://eclipse-metrics.sourceforge.net

Add to Array jQuery

For JavaScript arrays, you use push().

var a = [];
a.push(12);
a.push(32);

For jQuery objects, there's add().

$('div.test').add('p.blue');

Note that while push() modifies the original array in-place, add() returns a new jQuery object, it does not modify the original one.

How can I read Chrome Cache files?

The Google Chrome cache directory $HOME/.cache/google-chrome/Default/Cache on Linux contains one file per cache entry named <16 char hex>_0 in "simple entry format":

  • 20 Byte SimpleFileHeader
  • key (i.e. the URI)
  • payload (the raw file content i.e. the PDF in our case)
  • SimpleFileEOF record
  • HTTP headers
  • SHA256 of the key (optional)
  • SimpleFileEOF record

If you know the URI of the file you're looking for it should be easy to find. If not, a substring like the domain name, should help narrow it down. Search for URI in your cache like this:

fgrep -Rl '<URI>' $HOME/.cache/google-chrome/Default/Cache

Note: If you're not using the default Chrome profile, replace Default with the profile name, e.g. Profile 1.

Export to csv in jQuery

I recently posted a free software library for this: "html5csv.js" -- GitHub

It is intended to help streamline the creation of small simulator apps in Javascript that might need to import or export csv files, manipulate, display, edit the data, perform various mathematical procedures like fitting, etc.

After loading "html5csv.js" the problem of scanning a table and creating a CSV is a one-liner:

CSV.begin('#PrintDiv').download('MyData.csv').go();

Here is a JSFiddle demo of your example with this code.

Internally, for Firefox/Chrome this is a data URL oriented solution, similar to that proposed by @italo, @lepe, and @adeneo (on another question). For IE

The CSV.begin() call sets up the system to read the data into an internal array. That fetch then occurs. Then the .download() generates a data URL link internally and clicks it with a link-clicker. This pushes a file to the end user.

According to caniuse IE10 doesn't support <a download=...>. So for IE my library calls navigator.msSaveBlob() internally, as suggested by @Manu Sharma

SwiftUI - How do I change the background color of a View?

Several possibilities : (SwiftUI / Xcode 11)

1 .background(Color.black) //for system colors

2 .background(Color("green")) //for colors you created in Assets.xcassets

  1. Otherwise you can do Command+Click on the element and change it from there.

Hope it help :)

Can I install Python 3.x and 2.x on the same Windows computer?

I think there is an option to setup the windows file association for .py files in the installer. Uncheck it and you should be fine.

If not, you can easily re-associate .py files with the previous version. The simplest way is to right click on a .py file, select "open with" / "choose program". On the dialog that appears, select or browse to the version of python you want to use by default, and check the "always use this program to open this kind of file" checkbox.

Is there a command to list all Unix group names?

On Linux, macOS and Unix to display the groups to which you belong, use:

id -Gn

which is equivalent to groups utility which has been obsoleted on Unix (as per Unix manual).

On macOS and Unix, the command id -p is suggested for normal interactive.

Explanation of the parameters:

-G, --groups - print all group IDs

-n, --name - print a name instead of a number, for -ugG

-p - Make the output human-readable.

SSLHandshakeException: No subject alternative names present

Unlike some browsers, Java follows the HTTPS specification strictly when it comes to the server identity verification (RFC 2818, Section 3.1) and IP addresses.

When using a host name, it's possible to fall back to the Common Name in the Subject DN of the server certificate, instead of using the Subject Alternative Name.

When using an IP address, there must be a Subject Alternative Name entry (of type IP address, not DNS name) in the certificate.

You'll find more details about the specification and how to generate such a certificate in this answer.

How to import a jar in Eclipse

You can add a jar in Eclipse by right-clicking on the Project ? Build Path ? Configure Build Path. Under Libraries tab, click Add Jars or Add External JARs and give the Jar. A quick demo here.

enter image description here

The above solution is obviously a "Quick" one. However, if you are working on a project where you need to commit files to the source control repository, I would recommend adding Jar files to a dedicated library folder within your source control repository and referencing few or all of them as mentioned above.

What is the optimal way to compare dates in Microsoft SQL server?

You could add a calculated column that includes only the date without the time. Between the two options, I'd go with the BETWEEN operator because it's 'cleaner' to me and should make better use of indexes. Comparing execution plans would seem to indicate that BETWEEN would be faster; however, in actual testing they performed the same.

Display List in a View MVC

You are passing wrong mode to you view. Your view is looking for @model IEnumerable<Standings.Models.Teams> and you are passing var model = tm.Name.ToList(); name list. You have to pass list of Teams.

You have to pass following model

var model = new List<Teams>();

model.Add(new Teams { Name =  new List<string>(){"Sky","ABC"}});
model.Add(new Teams { Name =  new List<string>(){"John","XYZ"} });
return View(model);

Correct way to quit a Qt program?

You can call qApp.exit();. I always use that and never had a problem with it.

If you application is a command line application, you might indeed want to return an exit code. It's completely up to you what the code is.

How to stop a JavaScript for loop?

Use for of loop instead which is part of ES2015 release. Unlike forEach, we can use return, break and continue. See https://hacks.mozilla.org/2015/04/es6-in-depth-iterators-and-the-for-of-loop/

let arr = [1,2,3,4,5];
for (let ele of arr) {
  if (ele > 3) break;
  console.log(ele);
}

Mapping two integers to one, in a unique and deterministic way

We can encode two numbers into one in O(1) space and O(N) time. Suppose you want to encode numbers in the range 0-9 into one, eg. 5 and 6. How to do it? Simple,

  5*10 + 6 = 56. 
   
    5 can be obtained by doing 56/10 
    6 can be obtained by doing 56%10.

Even for two digit integer let's say 56 and 45, 56*100 + 45 = 5645. We can again obtain individual numbers by doing 5645/100 and 5645%100

But for an array of size n, eg. a = {4,0,2,1,3}, let's say we want to encode 3 and 4, so:

 3 * 5 + 4 = 19               OR         3 + 5 * 4 = 23
 3 :- 19 / 5 = 3                         3 :- 23 % 5 = 3
 4 :- 19 % 5 = 4                         4 :- 23 / 5 = 4

Upon generalising it, we get

    x * n + y     OR       x + n * y

But we also need to take care of the value we changed; so it ends up as

    (x%n)*n + y  OR x + n*(y%n)

You can obtain each number individually by dividing and finding mod of the resultant number.

Javascript loading CSV file into an array

If your not overly worried about the size of the file then it may be easier for you to store the data as a JS object in another file and import it in your . Either synchronously or asynchronously using the syntax <script src="countries.js" async></script>. Saves on you needing to import the file and parse it.

However, i can see why you wouldnt want to rewrite 10000 entries so here's a basic object orientated csv parser i wrote.

function requestCSV(f,c){return new CSVAJAX(f,c);};
function CSVAJAX(filepath,callback)
{
    this.request = new XMLHttpRequest();
    this.request.timeout = 10000;
    this.request.open("GET", filepath, true);
    this.request.parent = this;
    this.callback = callback;
    this.request.onload = function() 
    {
        var d = this.response.split('\n'); /*1st separator*/
        var i = d.length;
        while(i--)
        {
            if(d[i] !== "")
                d[i] = d[i].split(','); /*2nd separator*/
            else
                d.splice(i,1);
        }
        this.parent.response = d;
        if(typeof this.parent.callback !== "undefined")
            this.parent.callback(d);
    };
    this.request.send();
};

Which can be used like this;

var foo = requestCSV("csvfile.csv",drawlines(lines)); 

The first parameter is the file, relative to the position of your html file in this case. The second parameter is an optional callback function the runs when the file has been completely loaded.

If your file has non-separating commmas then it wont get on with this, as it just creates 2d arrays by chopping at returns and commas. You might want to look into regexp if you need that functionality.

//THIS works 

"1234","ABCD" \n
"!@£$" \n

//Gives you 
[
 [
  1234,
  'ABCD'
 ],
 [
  '!@£$'
 ]
]

//This DOESN'T!

"12,34","AB,CD" \n
"!@,£$" \n

//Gives you

[
 [
  '"12',
  '34"',
  '"AB',
  'CD'
 ]
 [
  '"!@',
  '£$'
 ]
]

If your not used to the OO methods; they create a new object (like a number, string, array) with their own local functions and variables via a 'constructor' function. Very handy in certain situations. This function could be used to load 10 different files with different callbacks all at the same time(depending on your level of csv love! )

Redirect all output to file in Bash

You can use exec command to redirect all stdout/stderr output of any commands later.

sample script:

exec 2> your_file2 > your_file1
your other commands.....

Comparing arrays in C#

Recommending SequenceEqual is ok, but thinking that it may ever be faster than usual for(;;) loop is too naive.

Here is the reflected code:

public static bool SequenceEqual<TSource>(this IEnumerable<TSource> first, 
    IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
    if (comparer == null)
    {
        comparer = EqualityComparer<TSource>.Default;
    }
    if (first == null)
    {
        throw Error.ArgumentNull("first");
    }
    if (second == null)
    {
        throw Error.ArgumentNull("second");
    }
    using (IEnumerator<TSource> enumerator = first.GetEnumerator())     
    using (IEnumerator<TSource> enumerator2 = second.GetEnumerator())
    {
        while (enumerator.MoveNext())
        {
            if (!enumerator2.MoveNext() || !comparer.Equals(enumerator.Current, enumerator2.Current))
            {
                return false;
            }
        }
        if (enumerator2.MoveNext())
        {
            return false;
        }
    }
    return true;
}

As you can see it uses 2 enumerators and fires numerous method calls which seriously slow everything down. Also it doesn't check length at all, so in bad cases it can be ridiculously slower.

Compare moving two iterators with beautiful

if (a1[i] != a2[i])

and you will know what I mean about performance.

It can be used in cases where performance is really not so critical, maybe in unit test code, or in cases of some short list in rarely called methods.

AndroidStudio: Failed to sync Install build tools

In case you have multiple SDKs locations (might happen if you play around with multiple Android Studio versions and create new location for SDK, what I did), make sure to check the local.properties file (both of the project and of your module, if you have such structure) and check if the line sdk.dir=/home/yourSdkLocation points indeed to the SDK you want to use.

This was the reason it wasn't working for me and it has fixed this.

What’s the difference between “{}” and “[]” while declaring a JavaScript array?

var a = [];

it is use for brackets for an array of simple values. eg.

var name=["a","b","c"]

var a={}

is use for value arrays and objects/properties also. eg.

var programmer = { 'name':'special', 'url':'www.google.com'}

Internet Access in Ubuntu on VirtualBox

I had a similar issue in windows 7 + ubuntu 12.04 as guest. I resolved by

  • open 'network and sharing center' in windows
  • right click 'nw-bridge' -> 'properties'
  • Select "virtual box host only network" for the option "select adapters you want to use to connect computers on your local network"
  • go to virtual box.. select the network type as NAT.

Read next word in java

You can just use Scanner to read word by word, Scanner.next() reads the next word

try {
  Scanner s = new Scanner(new File(filename));

  while (s.hasNext()) {
    System.out.println("word:" + s.next());
  }
} catch (IOException e) {
  System.out.println("Error accessing input file!");
}

Branch from a previous commit using Git

If you are not sure which commit you want to branch from in advance you can check commits out and examine their code (see source, compile, test) by

git checkout <sha1-of-commit>

once you find the commit you want to branch from you can do that from within the commit (i.e. without going back to the master first) just by creating a branch in the usual way:

git checkout -b <branch_name>