Iterate over each line in a string in PHP

Question

I have a form that allows the user to either upload a text file or copy paste the contents of the file into a textarea  I can easily differentiate between the two and put whichever one they entered into a string variable  but where do I go from there   I need to iterate over each line of the string  preferably not worrying about newlines on different machines   make sure that it has exactly one token  no spaces  tabs  commas  etc    sanitize the data  then generate an SQL query based off of all of the lines   I m a fairly good programmer  so I know the general idea about how to do it  but it s been so long since I worked with PHP that I feel I am searching for the wrong things and thus coming up with useless information  The key problem I m having is that I want to read the contents of the string line-by-line  If it were a file  it would be easy   I m mostly looking for useful PHP functions  not an algorithm for how to do it  Any suggestions

User · Answer

It s overly-complicated and ugly but in my opinion this is the way to go    fp   fopen  php   memory    r     fputs  fp   data   rewind  fp   while  line   fgets  fp         deal with  line   fclose  fp

User · Answer

I would like to propose a significantly faster  and memory efficient  alternative  strtok rather than preg split    separator     r n    line   strtok  subject   separator    while   line     false          do something with  line      line   strtok   separator        Testing the performance  I iterated 100 times over a test file with 17 thousand lines  preg split took 27 7 seconds  whereas strtok took 1 4 seconds   Note that though the  separator is defined as   r n   strtok will separate on either character - and as of PHP4 1 0  skip empty lines tokens   See the strtok manual entry   http   php net strtok

User · Answer

foreach preg split     r n       text  as  line       if empty  line  or ctype space  line   continue     skip only spaces        if  strlen  line   trim  line    continue     or trim by force and skip empty         line is trimmed and nice here so use it       this is how you break lines properly  cross-platform compatible with Regexp

User · Answer

Kyril s answer is best considering you need to be able to handle newlines on different machines        I m mostly looking for useful PHP functions  not an algorithm for how   to do it  Any suggestions     I use these a lot    explode   can be used to split a string into an array  given a single delimiter  implode   is explode s counterpart  to go from array back to string

User · Answer

preg split the variable containing the text  and iterate over the returned array   foreach preg split      r  n    r n        subject  as  line          do stuff with  line

User · Answer

If you need to handle newlines in diferent systems you can simply use the PHP predefined constant PHP EOL  http   php net manual en reserved constants php  and simply use explode to avoid the overhead of the regular expression engine    lines   explode PHP EOL   subject

User · Answer

Potential memory issues with strtok   Since one of the suggested solutions uses strtok  unfortunately it doesn t point out a potential memory issue  though it claims to be memory efficient   When using strtok according to the manual  the      Note that only the first call to strtok uses the string argument    Every subsequent call to strtok only needs the token to use  as it   keeps track of where it is in the current string    It does this by loading the file into memory  If you re using large files  you need to flush them if you re done looping through the file    lt  php function process  str         line   strtok  str  PHP EOL          do something with the first line here           while   line     FALSE               get the next line          line   strtok PHP EOL              do something with the rest of the lines here                   the bit that frees up memory     strtok              If you re only concerned with physical files  eg  datamining    According to the manual  for the file upload part you can use the file command      Create the array   lines   file   some file      foreach    lines as  line          do something here

[php] Iterate over each line in a string in PHP

Examples related to php

Examples related to string