PHP add leading zero

In order to format output, sometimes you need to add leading characters. PHP has a str_pad function that lets add leading or trailing characters to achieve string length.

In following snippet, you can see simple example of usage.

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function add_leading_zeros($input, $str_length) {
	return str_pad($input, $str_length, '0', STR_PAD_LEFT);
}
 
//example of usage (this will echo "0013")
echo add_leading_zeros('13', 4);