Week 3 Laboratory — Sample Solutions

  1. concat.c 

    // concat.c: print all command line arguments in a single line
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
   int i;

   printf("Name of the program: %s\n", argv[0]);
   printf("Number of arguments: %d\n", argc-1);
   for (i=1; i<argc; i++) {
      printf("%s", argv[i]);
   }
   putchar('\n');
   return EXIT_SUCCESS;
}

  2. add3.c 

    // add3.c: sum exactly 3 arguments from the command line
#include <stdio.h>
#include <stdlib.h>

#define NUMARGS 3

int main(int argc, char *argv[]) {
   int dataGood = 1;
   int retval = EXIT_SUCCESS;
   if (argc < 4 || argc > 4) {
      fprintf(stderr, "%s: incorrect number of args\n", argv[0]);
      dataGood = 0;
   } else {
      int sum = 0;
      int i;
      for (i=1; i<=NUMARGS && dataGood; i++) {
         int n;
         if (sscanf(argv[i], "%d", &n) == 1) {
            sum = sum + n;
         } else {
           fprintf(stderr, "%s: found non-numerical arg\n", argv[0]);
           dataGood = 0;
         }
      }
      if (dataGood) {
         printf("%d\n", sum);
      }
   }
   if (!dataGood) {
      retval = EXIT_FAILURE;
   }
   return retval;
}

  3. sumnum.c 

    // sumnum.c: sum the numbers on the command line
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
   int dataGood = 1;
   int retval = EXIT_SUCCESS;
   if (argc > 1) {
      int i, n;
      int sum = 0;
      for (i=1; i<argc && dataGood; i++) {
         if (sscanf(argv[i], "%d", &n) == 1) {
            sum = sum + n;
         } else {
            fprintf(stderr, "error: argument %s is non-numeric\n", argv[i]);
            dataGood = 0;
         }
      }
      if (dataGood) {
         printf("%d\n", sum);
      }
   }
   if (!dataGood) {
      retval = EXIT_FAILURE;
   }
   return retval;
}

    Makefile 

    CC=gcc
CFLAGS=-Wall -Werror -O

sumnum: sumnum.c
	$(CC) $(CFLAGS) -o $@ $<

countplus: countplus.c
	$(CC) $(CFLAGS) -o $@ $<

all: sumnum countplus

clean:
	rm -f sumnum.o countplus.o sumnum countplus core

  4. countplus.c 

    // countplus.c: iteratively count from 0 to argv[1],
// where argv[1] is a non-negative integer
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[]) {
   int retval;
   int endcount = 0;
   if ((argc != 2) || (sscanf(argv[1], "%d", &endcount) != 1)) {
      fprintf(stderr, "Usage: %s number\n", argv[0]);
      retval = EXIT_FAILURE;
   } else {
      int i;
      for (i=0; i<=endcount; i++) {
         printf("%d", i);
         if (i < endcount) {
            putchar(',');
         } else {
            putchar('\n');
         }
      }
      retval = EXIT_SUCCESS;
   }
   return retval;
}