Thread: Merge sort problem

i was writing a recursive code for mergesort .. and when i am executing it.
after entering the array .. program stopped working..
Please help me...
here's the code..

Code:

#include<stdio.h>
#include<conio.h>
#define MAX 20
int a[MAX];
int n;
int main()
{
    int i,j,k,l,m;
    printf("ENTER THE NUMBER OF TERMS\n");
    scanf("%d",&n);
    printf("ENTER THE ARRAY\n");
    for(i=0;i<n;i++)
    {
                     scanf("%d",&a[i]);
    }
               
      printf("Before Sorting\n");
      
    for(i=0;i<n;i++)
    {
                     printf("%d\n",a[i]);
    }                    
      printf("\n");
      
      mergesort(0,n-1);
      printf("AFTER SORTING");
          for(i=0;i<n;i++)
    {
                     printf("%d\n",a[i]);
    }                  
    
    
    
    
    getch();
            }
            
            
            
            mergesort(int low,int high)
            {
                      int mid;
             
                
                      if (low<high)
                      mid=(low+high)/2;
                      
                     mergesort(low,mid);
                     mergesort(mid+1,high);
                     merge(a,low,mid,high);
                     }
   merge( int a[],int low,int mid,int high )       
        {
             int i=0,j,k,lb;
             int b[high];
             lb=i=low,
             j=mid+1;
             while((lb<=mid)&&(j<high))
             {
                                       if(a[lb]<=a[j])
                                       {
                                                      b[i]=a[lb];
                                       lb=lb+1;
                                       }
                                       else
                                       {
                                           b[i]=a[j];
                                           j=j+1;
                                           }
                                           
                                       i=i+1;
                                       }
        if(lb>mid)
        {
                  for(k=j;k<=high;k++)
                  {
                           b[i]=a[k];
                           i=i+1;
                           }}
                           
                           else                                              
                           {
                              for(k=lb;k<=mid;k++)
                              {
                                      b[i]=a[k];
                                      i=i+1;
                                      }
                                      }
                                      
                                      
    for(k=low;k<=high;k++)
    {
        a[k]=b[k];
        }
        }

sorry i am new to coding.. had no idea about these styles..
it stopped working in the sense..
i am facing a problem somewhere in the functions...
i named the file as merge sort..
after i entered the array..
when the execution reaches the mergesort function call

program stopped working..
windows is checking for a solution to the problem..

"program stopped working..windows is checking for a solution to the problem.".

that typically means you accessed an illegal memory location or you corrupted the stack. in your case you are probably overrunning an array on the stack. and you have an array on the stack in your function 'merge'.

in your loops, check out everywhere you use '<=' which can be a source of overruns if your index goes 1 too many. like 'k<=high'.