Setting a pointer to NULL in C, not compiling

Question

for some reason, when I try to compile my code the .exe file just disappears after its done... without any errors or warnings.

This is what my code looks like:

#include <stdio.h>
#include <stdlib.h>

typedef struct student_ 
{
    int matnum;
    char vorname[20];
    struct student_ *next;
} student;

int main (int argc, char **argv) 
{
    student hans;
    hans.matnum = 12;

    student peter;
    peter.matnum = 13;
    peter.next = NULL; // THIS PART CAUSES MY PROBLEM

    hans.next = &peter;

    student *curr = &hans;
    while(curr != NULL)
    {
        printf("matnum: %d\n", (*curr).matnum);
        curr = curr->next;
    }

    return 0; 
}

What I want it to do is iterate through curr and set it to the next everytime curr wasn't NULL already. So if next is NULL, than the while-loop should stop.

peter.next = NULL; // THIS PART CAUSES MY PROBLEM

This is how I want to achieve that but it doesn't work. :\

From the comments:

I don't get an error. AFter I type in "gcc -Wall -o test test.c" the test.exe is there for a second and then it gets deleted.

This doesn't make any sense; either it compiles, or it doesn't and you get error messages. — Oliver Charlesworth
– Oliver Charlesworth, Commented May 11, 2014 at 9:26
Is it compilation error, or run time error? Can you please copy the error text and paste in your question? — Mohit Jain
– Mohit Jain, Commented May 11, 2014 at 9:27
I don't get an error. AFter I type in "gcc -Wall -o test test.c" the test.exe is there for a second and then it gets deleted. — user3233698
– user3233698, Commented May 11, 2014 at 9:29
Yes. But then the program crashes, which makes sense because the pointer curr is set to something that is not a student. — user3233698
– user3233698, Commented May 11, 2014 at 9:33

David Heffernan · Accepted Answer · 2014-05-11 09:33:39Z

6

The most plausible explanation for this is that your anti-virus software is deleting the executable. Your program compiles and runs fine here.

For whatever reason, the suspect line results in compiled code that your anti-virus software matches against a known virus. When you remove that line, it no longer matches the virus, but of course the program fails.

Temporarily disable your anti-virus to confirm this hypothesis.

answered May 11, 2014 at 9:33

David Heffernan

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2 Comments

user3233698 Over a year ago

Holy cow I turned avast off and it works now! Thank you a lot!

Mohit Jain Over a year ago

@David +1 it was out of the box

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