Example: String to Lowercase Manually in C

C
C++
C#
Java
Python
PHP
// String to Lowercase Manually
#include <stdio.h>
#include <string.h> // For strlen

void toLowerCaseManual(char *str) {
    // Step 1: Iterate through the string until the null terminator is found.
    for (int i = 0; str[i] != '\0'; i++) {
        // Step 2: Check if the current character is an uppercase English letter.
        // ASCII values: 'A' is 65, 'Z' is 90.
        if (str[i] >= 'A' && str[i] <= 'Z') {
            // Step 3: Convert to lowercase by adding 32 to its ASCII value.
            // (e.g., 'A' (65) + 32 = 'a' (97))
            str[i] = str[i] + 32;
        }
    }
}

int main() {
    char myString[] = "HELLO, WORLD! 123";

    printf("Original string: %s\n", myString);

    // Step 4: Call the toLowerCaseManual function.
    toLowerCaseManual(myString);

    printf("Lowercase string: %s\n", myString);

    return 0;
}