プログラミング1

replace.c

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

char swapcase(char c) {
  return isupper(c) ? tolower(c) : toupper(c);
}

void replace(char *src, char *dest) {
  size_t len = strlen(src);
  for (size_t i = 0; i < len; i++) {
    dest[i] = swapcase(src[i]);
  }
  dest[len] = '¥0';
}

int main(int argc, char *argv[]) {
  for (int i = 0; i < argc; i++){
    char dest[256];
    replace(argv[i], dest);
    printf("%s¥n", dest);
  }

  return 0;
}