is_string

(PHP 4, PHP 5)

is_stringFind whether the type of a variable is string

Description

bool is_string ( mixed $var )

Finds whether the type given variable is string.

Parameters

var

The variable being evaluated.

Return Values

Returns TRUE if var is of type string, FALSE otherwise.

Examples

Example #1 is_string() example

<?php
if (is_string("23")) {
    echo 
"is string\n";
} else {
    echo 
"is not a string\n";
}
var_dump(is_string('abc'));
var_dump(is_string("23"));
var_dump(is_string(23.5));
var_dump(is_string(true));
?>

The above example will output:

is string
bool(true)
bool(true)
bool(false)
bool(false)

See Also

  • is_float() - Finds whether the type of a variable is float
  • is_int() - Find whether the type of a variable is integer
  • is_bool() - Finds out whether a variable is a boolean
  • is_object() - Finds whether a variable is an object
  • is_array() - Finds whether a variable is an array

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User Contributed Notes 3 notes

up
0
laszlo dot heredy shift-two gmail etc
1 month ago
Using is_string() on an object will always return false (even with __toString()).

<?php
class B {
  public function
__toString() {
    return
"Instances of B() can be treated as a strings!\n";
  }


$b = new B();
print(
$b); //Instances of B() can be treated as a strings!
print(is_string($b) ? 'true' : 'false'); //false
?>
up
-5
slicky at newshelix dot com
13 years ago
Be aware that this function could result into unwanted results if you check single chars in an array.
For instance:
You have a simple string and want to repeat this string evertime it ends.

<?php
for ($i=0; $i < strlen($string);$i++){
    if(!
is_string($key[$x]))
       
$x = 0;
    echo
$key[$x];
   
$x++;
}
?>

This will print you out the key, but won't iterate it since $x won't be reset. is_string function will give out true at element in that string, even if it doesn't exist. for instance is_string $key[1000] while your string is just 10chars long.
However this doesn't matter just use $key[$x] == '' instead.
Of course you won't use this to iterate a string, but you might come across something where this get useful, for instance for a en/decrypt engine.
up
-18
Sammy Moshe
8 months ago
The cool thing about this function is that it lets you be a lot more specific with your logic than you could have been before. And since I'm all about explicit control, when it comes to code, this one gets me all hot and bothered.

<?php
    
//Like this. You could also do the reverse of it.
    
if(is_string($variable) ) && !is_array($variable) ){
         
//Do something that appeals to your controlling nature.
    
}

?>

God bless those php dev guys for thinking of everything.
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