krx70100.c

来自「answer of the c programming language sec」· C语言 代码 · 共 45 行

/* This program converts its input to upper case
 * (if argv[0] begins with U or u) or lower case.
 * If argc is 0, it prints an error and quits.
 */

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


int main(int argc, char **argv)
{
  int (*convcase[2])(int) = {toupper, tolower};
  int func;
  int result = EXIT_SUCCESS;

  int ch;

  if(argc > 0)
  {
    if(toupper((unsigned char)argv[0][0]) == 'U')
    {
      func = 0;
    }
    else
    {
      func = 1;
    }

    while((ch = getchar()) != EOF)
    {
      ch = (*convcase[func])((unsigned char)ch);
      putchar(ch);
    }
  }
  else
  {
    fprintf(stderr, "Unknown name. Can't decide what to do.\n");
    result = EXIT_FAILURE;
  }

  return result;
}