Merge 2 sorted arrays in C

Question

I'm writing code to merge 2 sorted arrays code is below

void main()
{
    int a[]={7};
    int b[] = {8};
    int ret;
    int *c;
    merge(a,b,c,1,1);
}
void merge(int *a, int *b,int *sorted, int i, int j)
{
    int c1,c2,k=0;
    c1=0;
    c2=0;

    for(k=0;c1<i && c2< j;k++)
    {
        if(a[c1]<b[c2])
            sorted[k]=a[c1++];
        else
            sorted[k]=b[c2++];
    }
    while(c1<i)
        sorted[k++]=a[c1++];
    while(c2<j)
        sorted[k++]=b[j++];
}

When running this code program stops and I get the below exception

Problem Event Name: APPCRASH
  Application Name: merge.exe
  Application Version:  0.0.0.0
  Application Timestamp:    556fb91c
  Fault Module Name:    merge.exe
  Fault Module Version: 0.0.0.0
  Fault Module Timestamp:   556fb91c
  Exception Code:   c0000005
  Exception Offset: 00001739
  OS Version:   6.1.7601.2.1.0.768.3
  Locale ID:    2057
  Additional Information 1: 0a9e
  Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
  Additional Information 3: 0a9e
  Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

How to fix it

Answer 1

The problem is that you did not provide any space in which the merged information should be placed. You provided an uninitialized pointer c for the sorted parameter, which gets dereferenced inside the function, causing undefined behavior.

To fix this, pass an array with sufficient capacity to hold elements of the merged array:

int a[]={7, 15, 20};
int b[] = {8, 12, 19, 32};
int c[7];
merge(a, b, c, 3, 4);