text: #include <stdio.h>
  #include <stdlib.h>
  #include <ctype.h>
  
  int main(int argc, char * argv[]) {
  
      int i;
      for (i = 0; i < argc; i++) {
          if (isdigit(*argv[i])) {
              printf("%s is a digit!\n", argv[i]);
          }
          else {
              printf("%s is NOT a digit...\n", argv[i]);
          }
      }
  
      exit(EXIT_SUCCESS);
  }
  