Solution Exercise 52 : python algorithm to transform given a string into uppercase

Exercise 52

Using (Exercise 51), write a python program as a function which takes a string s as input and returns the same string in uppercase without using the upper() method. You can use the chr() and ord() methods.

Solution

def uppercase_string(s):
    result = ""
    for letter in s:
        if 97 <= ord(letter) <= 122: # check if letter is lowercase
            result += chr(ord(letter) - 32) # convert to uppercase and append to result
        else:
            result += letter # if not lowercase, simply append to result
    return result
# Example
s = 'Python programming'
print(uppercase_string(s)) # output: 'PYTHON PROGRAMMING'

Explanation:

1. This function takes a string s: as input and returns the uppercase version of the same string without using the built-in upper() method.
2. The function works by iterating: over each character in the string and checking whether it is a lowercase letter (which have ASCII codes between 97 and 122).
3. If the character is a lowercase letter: the function subtracts 32 from its ASCII code (which converts it to the corresponding uppercase letter) using chr() and appends it to the result string.
4. If the character is not a lowercase letter: it is simply appended to the result string as is.
5. Finally: the function returns the result string.

Younes Derfoufi
my-courses.net