We can check built in function or user defined functions before using them. The built in function function_exists checks this and returns true of false. It takes one string input and returns Boolean output. Here is an example.
if(function_exists(is_int)){
echo " Yes this function is available to use ";
}else{
echo " Sorry , this is not available to use " ;
}
In the above code we have used is_int() which is a built in function in PHP, so we will get the output as this.
Yes this function is available to use
User defined functions
<?Php
function my_function($var1,$var2,$var3){
$var=$var1+$var2+$var3;
return $var;
}
echo my_function(5,6,8); // Output 19
if(function_exists(is_int)){
echo " <br>Yes <i>my_function</i> is available to use ";
}else{
echo " <br>Sorry , <i>my_function</i> is not available to use " ;
}
?>