Read numeric input data from argv and store into an array of int in C

Question

How can I read triples of numbers from the program arguments into an array of integers and then display them? That is I enter ./read 1,2,3 4,5,6 7,8,9 and the ouptput should be

1 2 3

4 5 6

7 8 9

My code works well only for strings, but not integers

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

int main(int argc, char **argv)
{
  int i;
  int d[argc][3];
  int x[3];
  for(i = 1; i < argc; i ++){
      char *a[3];
      int j = 0;
      a[j] = strtok(argv[i], ",");
      while(a[j] != NULL){
        a[++j] = strtok(NULL, ",");
        x[j] = atoi(&(a[j]));
      }
      printf("%s %s %s \n", a[0], a[1], a[2]);
      printf("%d %d %d \n", x[0], x[1], x[2]);
    }
    return 0;
}

It displays 1 0 0 on each line.

when strtok() fails, then this line: x[j] = atoi(&(a[j])); (which is written incorrectly, it should be; x[j] = atoi(a[j]); will be accessing memory at address 0. This is almost certain to result in a access violation seg fault event. I.E. always check (!=NULL) the returned value from strtok() before de-referencing that value — user3629249
– user3629249, Commented Jan 13, 2016 at 14:49

Community · Accepted Answer · 2017-05-23 10:28:22Z

2

Here you have an error
```
x[j] = atoi(&(a[j]));
```
you should not pass the address like that, just
```
x[j] = atoi(a[j]);
```
should work.
You must include stdlib.h
You must check against NULL after strtok(). Or to do it correctly follow this comment by @BLUEPIXY.

x[j] = atoi(a[j]); then a[++j] = strtok(NULL, ",");

Enabling compiler warnings should have let you find this yourself.

edited May 23, 2017 at 10:28

CommunityBot

11 silver badge

answered Jan 12, 2016 at 20:08

Iharob Al Asimi

53.1k6 gold badges66 silver badges100 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Read numeric input data from argv and store into an array of int in C

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related