In PHP, this function returns a part of a string.

    substr(string,start,length)

In the above syntax given "string" is input to return , "start" specifies where to start in the input, "length" specifies the length of the part of a string.Usually the "start","length" can have positive and negative number,which refers to starting and ending of a string.

    <?php
    echo substr("abcdef", -1);
    echo substr("abcdef", -2);  
    echo substr("abcdef", 0, -1);  
    echo substr("abcdef", 2, -1);  
    ?>

    f
    ef
    abcde
    cde

In the above example first the start value is "-1" so last character "f" is taken, in another example start value is "0" so the string from the start is taken and since length is "-1" it leaves a character from the end to display output.