can anyone explain what the function ord does in this code? The code is meant to multiply the numbers written as strings (without using int()).
def multiply(num1, num2):
"""
:type num1: str
:type num2: str
:rtype: str
"""
res1, res2 = 0, 0
for d in num1:
print(d)
print(ord(d))
print(ord('0'))
res1 = res1 * 10 + (ord(d) - ord('0'))
for d in num2:
res2 = res2 * 10 + (ord(d) - ord('0'))
return str(res1 * res2)
How can ord(d) - ord('0') finally return the correct result. I don't understand what exactly ord does.
Is ord('0') always 48 (which is what I get when I print)?
ord is a function that takes a character and returns the number that unicode associates that character with. The way unicode structures the digits 0-9 ord("9")-ord("0") will result in 9. ord of 0 is 48 and the digits count up from there: "1" is 49, "2" is 50 etc. That code removes the offset of the digits in unicode so that you get the number that the digit is in order. So ord("2") - ord("0") evaluates to 50 - 48 which is 2.
The inverse of ord is chr which will return the character given a number. chr(48) is "0" You can play around with these functions as well as looking at an Ascii Table (which is contained in unicode) to learn more about how characters are represented in computers.