“Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset” using PHP

Question

I\'m running a PHP script and continue to receive errors like:

Notice: Undefined variable: my_variable_name in C:\\wamp\\www\\mypath\\index.php on line 10

Answer 1

In PHP you need fist to define the variable after that you can use it.
We can check variable is defined or not in very efficient way!.

//If you only want to check variable has value and value has true and false value.
//But variable must be defined first.

if($my_variable_name){

}

//If you want to check variable is define or undefine
//Isset() does not check that variable has true or false value
//But it check null value of variable
if(isset($my_variable_name)){

}

Simple Explanation

//It will work with :- true,false,NULL
$defineVarialbe = false;
if($defineVarialbe){
    echo "true";
}else{
    echo "false";
}

//It will check variable is define or not and variable has null value.
if(isset($unDefineVarialbe)){
    echo "true";
}else{
    echo "false";
}