toupper Function

Convert a character to an uppercase alphabetical character.

Include

<ctype.h>

Prototype

int toupper (int c);

Argument

c

The character to convert to uppercase.

Return Value

Returns the corresponding uppercase alphabetical character if the argument, c, was originally lowercase; otherwise, returns the original character.

Remarks

Only lowercase alphabetical characters may be converted to uppercase.

Example

#include <ctype.h>
#include <stdio.h>

int main(void)
{
  int ch;

  ch = 'b';
  printf("b changes to uppercase %c\n",
          toupper(ch));

  ch = 'B';
  printf("B remains uppercase %c\n",
          toupper(ch));

  ch = '@';
  printf("@ has no uppercase, ");
  printf("so %c is returned\n", toupper(ch));
}

Example Output

b changes to uppercase B
B remains uppercase B
@ has no uppercase, so @ is returned