to… Functions

2.2.2 to… Functions

Declarations:

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:

tolowerIf the character is an uppercase character (A to Z), then it is converted to lowercase (a to z)
toupperIf 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;
}
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