#include <stdio.h>
#include <ctype.h>

void convertToUpper(char *str) {
    while (*str) {
        *str = toupper((unsigned char) *str);
        str++;
    }
}

void convertToLower(char *str) {
    while (*str) {
        *str = tolower((unsigned char) *str);
        str++;
    }
}

void convertToUpper1(char *str) {
    for(int i = 0; str[i] != '\0'; i++)
        str[i] = toupper((unsigned char)str[i]);
}

void convertToLower1(char *str) {
    for(int i = 0; str[i] != '\0'; i++)
        str[i] = tolower((unsigned char)str[i]);

}

int main() {
    char myString[] = "Hello, World!";
    printf("original message: %s\n", myString);

    convertToUpper(myString);
    printf("Uppercase: %s\n", myString);

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

    convertToUpper1(myString);
    printf("uppercase: %s\n", myString);

    convertToLower1(myString);
    printf("lowercase: %s\n", myString);
    return 0;
}