CODEWITHSUNDEEP
cgccsegmentation-fault
skeytrek
skeytrek

Reputation: 53

Segmentation fault in a function

I want to find the address of an integer in an array. Debugger revealed that line 8 is at fault. if (*i==item) {ans=i;};

Variable ans is local and not null, yet segmentation fault occurs. Why is that and how can I fix it?

#include <stdio.h>

int* finder(int *begin, int *end, int item)
{
    int *ans=0; int *i=begin;

    while (i<end) {
        if (*i==item) {ans=i;};
        i++;
    }

    return ans;
}

int main()
{
    int arSize, target, i=0;
    int arr[10]={};
    int *first=&arr[0]; int *last; int *result;

    printf("Find element: ");
    scanf("&d",&target);
    printf("Array size: ");
    scanf("&d",&arSize);
    printf("Enter array: ");
    while (i<arSize){
        scanf("&d",&arr[i]);
        i++;
    }

    last=&arr[arSize];
    result=finder(first,last,target);

    printf("%s %p","Target's address is ",result);


    return 0;
}

Upvotes: 2

Views: 82

Answers (2)

VillageTech
VillageTech

Reputation: 2015

Probably it fails on the last iteration inside finder() in case the arSize is equal 10.

You declared an array 'arr[10]', so it means that the index of the last element is equal 9, not 10 :)

So, you should change one line in main():

last=&arr[arSize];

to:

last=&arr[arSize-1];

Of course, you should always check that arSize is <= 10.

Upvotes: 0

dash-o
dash-o

Reputation: 14493

The scanf() format have typo: they use '&' instead of '%. As a result, the program (as posted) does not read any input.

Suggestion: make sure you get CLEAN compile (no warning, no errors) before trying to run (or debug). GCC flagged the format errors with the default 'cc'.

ff.c:22:11: warning: too many arguments for format [-Wformat-extra-args]

 scanf("&d",&target);
       ^~~~

3 fixes are needed.

  • scanf("&d",&target);
  • scanf("&d",&arSize);
  • scanf("&d",&arr[i]);

For example: 

    printf("Array size: ");
// BAD:    scanf("&d",&arSize);
    scanf("%d",&arSize);

Code seems to run fine on simple cases with this fix.

Upvotes: 4

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