Signature
String substr(String s, s64 start_pos) String substr(String s, s64 start_pos, s64 length)
Parameters
s : source string
start_pos : zero-based start position; negative values count from the end of the string
length : optional substring length; negative values trim bytes from the end of the result range
return value : extracted substring, or an empty string if the requested range is outside the source string
Extracts part of a string using PHP-style start and length semantics.
Use the two-argument form to return everything from start_pos to the end of the string.
If start_pos is negative, counting starts from the end of the string.
If length is negative, the returned range stops that many bytes before the end of the string.
Example
print(substr("documentation", 0, 3), "\n");
Output
doc