# toupper

From cppreference.com
< c‎ | string‎ | byte

Defined in header `<ctype.h>` |  |
int toupper( int ch ); |  |

Converts the given character to uppercase according to the character conversion rules defined by the currently installed C locale.

In the default "C" locale, the following lowercase letters `abcdefghijklmnopqrstuvwxyz` are replaced with respective uppercase letters `ABCDEFGHIJKLMNOPQRSTUVWXYZ`.

### Parameters

ch | - | character to be converted. If the value of `ch` is not representable as unsigned char and does not equal EOF, the behavior is undefined.

### Return value

Uppercase version of `ch` or unmodified `ch` if no uppercase version is listed in the current C locale.

### Example

Run this code

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

    int main(void)
    {
        /* In the default locale: */
        unsigned char u;
        for (unsigned char l=0; l<UCHAR_MAX; l++) {
            u = toupper(l);
            if (l!=u) printf("%c%c ", l,u);
        }
        printf("\n\n");

        unsigned char c = '\xb8'; // the character Ž in ISO-8859-15
                                  // but ´ (acute accent) in ISO-8859-1
        unsigned char c2 = c;   // for printing
        setlocale(LC_ALL, "en_US.iso88591");
        printf("in iso8859-1, toupper('0x%x') gives 0x%x\n", c2, toupper(c));
        setlocale(LC_ALL, "en_US.iso885915");
        printf("in iso8859-15, toupper('0x%x') gives 0x%x\n", c2, toupper(c));
    }

Output:

    aA bB cC dD eE fF gG hH iI jJ kK lL mM nN oO pP qQ rR sS tT uU vV wW xX yY zZ

    in iso8859-1, toupper('0xb8') gives 0xb8
    in iso8859-15, toupper('0xb8') gives 0xb4

### References

- C11 standard (ISO/IEC 9899:2011):

  - 7.4.2.2 The toupper function (p: 204)

- C99 standard (ISO/IEC 9899:1999):

  - 7.4.2.2 The toupper function (p: 185)

- C89/C90 standard (ISO/IEC 9899:1990):

  - 4.3.2.2 The toupper function

### See also

tolower | converts a character to lowercase (function)
towupper (C95) | converts a wide character to uppercase (function)

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