tolower(), toupper() — Convert character case
Standards
| Standards / Extensions | C or C++ | Dependencies |
|---|---|---|
ISO C
POSIX.1 XPG4 XPG4.2 C99 Single UNIX Specification, Version 3 |
both |
Format
#include <ctype.h>
int tolower(int c); /* Convert c to lowercase if appropriate */
int toupper(int c); /* Convert c to uppercase if appropriate */General description
Converts c to a lowercase letter, if possible. Conversely, the toupper() function converts c to an uppercase letter, if possible.
The DBCS is not supported. The use of characters from the DBCS results in unspecified behavior.
Returned value
If successful, tolower() and toupper() return the corresponding character, as defined in the LC_CTYPE category of the current locale, if such a character exists.
If unsuccessful, tolower() and toupper() return the unchanged value c.
Example
CELEBT15
/* CELEBT15
This example demonstrates the result of using
&toupper. and &tolower. on a lower-case a.
*/
#include <stdio.h>
#include <ctype.h>
int main(void)
{
int ch;
ch = 0x81;
printf("toupper=%#04x\n", toupper(ch));
printf("tolower=%#04x\n", tolower(ch));
}