How can one handle undefined variables in PHP to avoid errors like "$spielerinfo3 is not defined"?

To handle undefined variables in PHP and avoid errors like "$spielerinfo3 is not defined," you can use the isset() function to check if a variable is set before trying to use it. This way, you can prevent errors by ensuring that the variable exists before attempting to access its value.

if(isset($spielerinfo3)) {
    // Variable is set, do something with it
    echo $spielerinfo3;
} else {
    // Variable is not set, handle the case accordingly
    echo "Variable spielerinfo3 is not defined.";
}