Format
#include <ctype.h> int tolower(int C); int toupper(int c);
Language Level: ANSI, POSIX, XPG4
tolower converts the uppercase letter C to the
corresponding lowercase letter.
toupper converts the lowercase letter c to the corresponding uppercase letter.
The character mapping is determined by the LC_CTYPE category of the current locale.
Return Value
Both functions return the converted character. If the
character c does not have a corresponding lowercase of
uppercase character, the functions return c unchanged.
Example
This example uses toupper and tolower to modify
characters between code 0 and code 7f.
#include <stdio.h> #include <ctype.h>
int main(void)
{
int ch;
for (ch = 0; ch <= 0x7f; ch++)
{
printf("toupper=%#04x\n", toupper(ch));
printf("tolower=%#04x\n", tolower(ch));
putchar('\n');
}
return 0;
}
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isalnum to isxdigit -- Test Integer Value
isascii -- Test Integer Values
_iscsym - _iscsymf -- Test Integer
_toascii - _tolower - _toupper --
Convert Character
towlower - towupper -- Convert Wide
Character Case
<ctype.h>