Using the toupper() function in C

The toupper() function in C is used to convert a lowercase character to its uppercase counterpart. For example, the toupper() function would convert the character 'a' to 'A'.

The toupper() function takes a character as input and returns the converted character.

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

int32_t main(int32_t argc, char const *argv[])
{
    char c = 'a';
    char upper_c = toupper(c);
    printf("The uppercase version of '%c' is '%c'.\n", c, upper_c);

    return 0;
}

Converts lowercase letters to uppercase. Returns the uppercase equivalent to letters, if such value exists, else letters remains unchanged. The character’s value must be representable as an unsigned char or the value of EOF.

Explore the complete list of functions available in ctype header in C standard library.