Why a function checking if a string is empty always returns true

Question

I have a function isNotEmpty which returns true if the string is not empty and false if the string is empty  I ve found out that it is not working if I pass an empty string through it    function isNotEmpty  input          strTemp    input       strTemp   trim  strTemp        if strTemp          Also tried this  if strlen  strTemp   gt  0                  return true             return false      The validation of the string using isNotEmpty is done   if isNotEmpty  userinput  phoneNumber             validate the phone number   else       echo  Phone number not entered lt br  gt        If the string is empty the else doesn t execute  I don t understand why  can someone please shed some light on this please

User · Answer

I always use a regular expression for checking for an empty string, dating back to CGI/Perl days, and also with Javascript, so why not with PHP as well, e.g. (albeit untested)

return preg_match('/\S/', $input);

Where \S represents any non-whitespace character

User · Answer

this is the short and effective solution  exactly what you re looking for    return  input  gt  null    not empty     empty

User · Answer

I just write my own function  is string for type checking and strlen to check the length   function emptyStr  str        return is string  str   amp  amp  strlen  str      0     print emptyStr        empty     not empty      empty   Here s a small test repl it  EDIT  You can also use the trim function to test if the string is also blank   is string  str   amp  amp  strlen trim  str       0

User · Answer

In your if clause in the function  you re referring to a variable strTemp that doesn t exist   strTemp does exist  though   But PHP already has an empty   function available  why make your own   if  empty  str          String is empty    else        Not empty      From php net      Return Values      Returns FALSE if var has a non-empty   and non-zero value       The following things are considered to   be empty         an empty string    0  0 as an integer     0   0 as a string    NULL   FALSE   array    an empty array    var  var   a variable declared  but without a value in a class     http   www php net empty

User · Answer

You can simply cast to bool  dont forget to handle zero   function isEmpty string  string   bool       if  string      0             return false            return   bool  string     var dump isEmpty          bool true  var dump isEmpty  foo        bool false  var dump isEmpty  0        bool false

User · Answer

I know this thread been pretty old but I just wanted to share one of my function  This function below can check for empty strings  string with maximum lengths  minimum lengths  or exact length  If you want to check for empty strings  just put  min len and  max len as 0   function chk str   input   min len   null   max len   null         if    is int  min len   amp  amp   min len     null   throw new Exception  chk str     min len must be an integer or a null value         if    is int  max len   amp  amp   max len     null   throw new Exception  chk str     max len must be an integer or a null value           if    min len     null  amp  amp   max len     null             if    min len  gt   max len   throw new Exception  chk str     min len can  t be larger than  max len                if    is string   input               return false        else            output   true             if    min len     null            if   strlen  input   lt   min len    output   false             if    max len     null            if   strlen  input   gt   max len    output   false             return  output

User · Answer

PHP evaluates an empty string to false  so you can simply use   if  trim  userinput  phoneNumber            validate the phone number   else     echo  Phone number not entered lt br  gt

User · Answer

if you have a field namely serial number and want to check empty then   serial number   trim   POST serial number     q  select   from product where user id    SESSION id      rs mysql query  q   while  row mysql fetch assoc  rs    if empty   POST  irons       irons  row  product1        in this way you can chek all the fileds in the loop with another empty function

User · Answer

PHP have a built in function called empty   the test is done by typing  if empty  string        Reference php net   php empty

User · Answer

Just use  strlen   function  if  strlen  s           not empty

User · Answer

Well here is the short method to check whether the string is empty or not    input    Assuming to be the string   if strlen  input   0   return false   if the string is empty   else  return true    if the string is not empty

User · Answer

Simple problem actually  Change   if  strTemp          to   if   strTemp          Arguably you may also want to change it to   if   strTemp           since       will return true if you pass is numeric 0 and a few other cases due to PHP s automatic type conversion   You should not use the built-in empty   function for this  see comments and the PHP type comparison tables

User · Answer

You got an answer but in your case you can use   return empty  input     or   return is string  input

User · Answer

I needed to test for an empty field in PHP and used   ctype space  tempVariable    which worked well for me

[php] Why a function checking if a string is empty always returns true?

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