谁能解析vc++6.0怪现象?

同一c文件,在win-tc上调试输入66,输出是0;在vc++6.0上调试输入66,输出7;为什么会是这样???该c文件是[gg.c],内容是:
#include<stdio.h>
#include<conio.h>
int fun(int a[],int n,int x)
{
    int i,j,mid,k=-1;
    i=0;j=n;
    while(i<=j)
    {
        mid=(i+j)/2;
        if(x>a[mid])
            i=mid+1;
        else if(x<a[mid])
            j=mid-1;
        else if(x==a[mid])
        {k=mid;break;}
        
    }
    return(k+1);
}
main()
{
    int i,l,a[6]={2,5,6,8,9,10};
    for(i=0;i<6;i++)
    {
        printf("%d ",a[i]);
    }
    scanf("%d",&l);
    l=fun(a,6,l);
    printf("\n%d\n",l);
    getch();
}
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