toupper

 

C

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Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (哋它亢99)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to and from numeric formats
atoiatolatoll (哋它亢99) atof strtolstrtoll (哋它亢99) strtoulstrtoull (哋它亢99)	strtoimaxstrtoumax (哋它亢99)(哋它亢99) strtofstrtodstrtold (哋它亢99)(哋它亢99) strfromfstrfromdstrfroml (哋它亢23)(哋它亢23)(哋它亢23)
String manipulation
strcpystrcpy_s (哋它亢11) strncpystrncpy_s (哋它亢11) strcatstrcat_s (哋它亢11)	strncatstrncat_s (哋它亢11) strxfrm strdup (哋它亢23) strndup (哋它亢23)
String examination
strlenstrnlen_s (哋它亢11) strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtokstrtok_s (哋它亢11)
Memory manipulation
memchr memcmp memsetmemset_explicitmemset_s (哋它亢23)(哋它亢11)	memcpymemcpy_s (哋它亢11) memmovememmove_s (哋它亢11) memccpy (哋它亢23)
Miscellaneous
strerrorstrerror_sstrerrorlen_s (哋它亢11)(哋它亢11)

 

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: */
    for (unsigned char l = 0; l < UCHAR_MAX; l++) {
        unsigned char u = toupper(l);
        if (u != l) 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 
    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

References

• 哋它亢17 standard (ISO/IEC 9899:2018):

• 7.4.2.2 The toupper function (p: 147-148)

• 哋它亢11 standard (ISO/IEC 9899:2011):

• 7.4.2.2 The toupper function (p: 204)

• 哋它亢99 standard (ISO/IEC 9899:1999):

• 7.4.2.2 The toupper function (p: 185)

• 哋它亢89/C90 standard (ISO/IEC 9899:1990):

• 4.3.2.2 The toupper function

See also

tolower	converts a character to lowercase (function)
towupper (哋它亢95)	converts a wide character to uppercase (function)