why this segmentation fault (core dumped) ??? int main (int argc, char *argv[])

Question

int main (int argc, char *argv[])
{
    int a, b, quo, rest;

    void division(int dividendo, int divisor, int *ptr_quociente, int *ptr_resto)
    {
        *ptr_quociente=dividendo/divisor;
        *ptr_resto=dividendo%divisor;
    }

    if(argc=3)
    {
        a= atoi(argv[1]);   
        b= atoi(argv[2]);    

        division(a,b,&quo,&rest);

        printf(" %d and %d \n",quo,rest);
    }
    else if (argc=1)
        do
        {
            printf("type two int numbers:\n");

            scanf("%d %d", &a, &b);

            division(a,b,&quo,&rest);

            printf(" %d and %d \n",quo,rest);

        } while(a!=0);
}

if I do:

./program.c 12 6

it works but if I do:

./program.c

I get a segmentation fault, why?

thank you! i should have seen it, kind of tired... – Bryant2 Mar 05 '14 at 04:39 — Bryant2, Mar 05 '14 at 04:39

score 2 · Accepted Answer · edited Mar 05 '14 at 04:40

2

 if(argc=3) should be if(3 == arc) //notice '=='

That's why it is always good idea to keep constant on LHS, this will avoid accidental assignment

Same with arc=1

Also, I moved local function definition outside main.

void division(int dividendo, int divisor, int *ptr_quociente, int *ptr_resto)

{

       *ptr_quociente=dividendo/divisor;
       *ptr_resto=dividendo%divisor;
}

int main (int argc, char *argv[])

{
...
}

Edit: After reading comments from Paxdiablo and Shafik, I came to know most modern compiler would warn for '=' in condition. You can simply write if(argc == 3) rather than placing constant on LHS.

edited Mar 05 '14 at 04:40

paxdiablo

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answered Mar 05 '14 at 04:31

Digital_Reality

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Bah, that's what I like to call "butt-ugly format", especially since modern compilers can warn about assignments within conditionals. But +1 anyway since you found the problem, even as I laugh derisively at your solution :-) – paxdiablo Mar 05 '14 at 04:34
Ack no, [Yoda condition we need not use with a modern compiler](http://stackoverflow.com/questions/22106713/what-is-the-difference-between-if-null-pointer-vs-if-pointer-null). – Shafik Yaghmour Mar 05 '14 at 04:34
@paxdiablo Shafik, yes kind of agree, as it is defensive programming than anything else. if(arc == 3) should be fine. – Digital_Reality Mar 05 '14 at 04:37

why this segmentation fault (core dumped) ??? int main (int argc, char *argv[])

1 Answers1