< 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.


[edit] 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.

[edit] Return value

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

[edit] Example

#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);
    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));


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

[edit] References

  • C11 standard (ISO/IEC 9899:2011):
  • The toupper function (p: 204)
  • C99 standard (ISO/IEC 9899:1999):
  • The toupper function (p: 185)
  • C89/C90 standard (ISO/IEC 9899:1990):
  • The toupper function

[edit] See also

converts a character to lowercase
converts a wide character to uppercase
C++ documentation for toupper