将指向数组的指针作为函数的参数传递

Question

I am trying to implement INSERTION SORT here in C , which I think I've done successfully. However, I am having problems in passing arrays as arguments .

I want in place sorting, which means that the original array passed into the insertion_sort function should contain the elements in the sorted array itself.

#include<stdio.h>

int * insertion_sort(int *a,int length)
{
    int j;
    for(j=1;j<length;j++)
    {
        int i,key=a[j];
        for(i=j-1;j>=0;j--)
        {
            if(a[i]<=key)
                break;
            a[i+1]=a[i];
        }  
        a[i+1]=key;
    }

    return *a;
}

int main(void)
{
    int a[]={10,12,7,6,9,8};
    insertion_sort(a,6);
    int i;    
    for(i=0; i<6; i++)
       printf("%d\n", a[i]);

    return 0;
}

EDIT Nothing gets printed in the output screen. Help me find the bug here. Thanks !!

Answer 1

1.You probably meant to use i in the inner loop:

Change:

for(i=j-1;j>=0;j--) 
          ^^   ^^

to:

for(i=j-1;i>=0;i--)

2.You don't have to return anything as the original array gets modified (which is just as well since you ignore the returned value).

3.Array index starts from 0. Change outer loop to: for(j=0;j<length;j++)