toupper - cppreference.com (original) (raw)
| | | | | ---------------------- | | | | 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 <ctype.h> #include <limits.h> #include <locale.h> #include <stdio.h> int main(void) { // in the default locale: for (unsigned char l = 0, u; l != UCHAR_MAX; ++l) if ((u = toupper(l)) != l) printf("%c%c ", l, u); printf("\n\n"); unsigned char c = '\xb8'; // the character ž in ISO-8859-15 // but ¸ (cedilla) in ISO-8859-1 setlocale(LC_ALL, "en_US.iso88591"); printf("in iso8859-1, toupper('0x%x') gives 0x%x\n", c, toupper(c)); setlocale(LC_ALL, "en_US.iso885915"); printf("in iso8859-15, toupper('0x%x') gives 0x%x\n", c, toupper(c)); }
Possible 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
[edit] References
C23 standard (ISO/IEC 9899:2024):
7.4.2.2 The toupper function (p: TBD)
C17 standard (ISO/IEC 9899:2018):
7.4.2.2 The toupper function (p: 147-148)
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