Converting strings to integers is one of common tasks.
Here we'll show how to convert decimal strings to integers.
Psuedo code to do this is:
function string_to_integer(str): result = 0 for (each characters in str, left to right): result = result * 10 add ((code of the character) - (code of character 0)) to result return result
Dealing with hexadecimal strings is a bit more difficult because character codes are typically not continuous when dealing with multiple character types such as digits(0-9) and alphabets(a-f and A-F). Character codes are typically continuous when dealing with only one type of characters (we'll deal with digits here), so we'll deal with only environments in which character codes for digit are continuous.