int tolower(int character);
int toupper(int character);
The to... functions provide a means to convert a single
character. If the character matches the appropriate condition,
then it is converted. Otherwise the character is returned
unchanged.
Conditions:
tolower
If the character is an uppercase
character (A to Z), then it is converted to lowercase (a
to z)
toupper
If the character is a lowercase
character (a to z), then it is converted to uppercase (A
to Z)
Example:
#include<ctype.h>
#include<stdio.h>
#include<string.h>
int main(void)
{
int loop;
char string[]="THIS IS A TEST";
for(loop=0;loop<strlen(string);loop++)
string[loop]=tolower(string[loop]);
printf("%s\n",string);
return 0;
}
