Returns an integer that is the number of characters in a string
(strlen [string]...)
An integer. If multiple string arguments are provided, strlen returns the sum of the lengths of all arguments. If you omit the arguments or enter an empty string, strlen returns 0.
Command: (strlen "abcd")
4
Command: (strlen "ab")
2
Command: (strlen "one" "two" "four")
10
Command: (strlen)
0
Command: (strlen "")
0