C语言二分查找（折半查找）

#include <stdio.h>
#include<stdlib.h>
int BinarySearch( int a[], int X )
{
    
    
    int low=1,high=10,mid;
    while(low<=high){
    
    
        mid=(high+low)/2;
        if(a[mid]>X) high-=1;
        else if(a[mid]<X) low+=1;
        else return mid;
    }
    return 0;
}    
void printarr(int a[],int n){
    
    
	for(int i=0;i<n;i++){
    
     
		printf("%d ",a[i]);
	}
	printf("\n");//养成好习惯 
}
void mergesort(int arr[], int len) {
    
    
    int* a = arr;
    int* b = (int*) malloc(len * sizeof(int));
    int seg, start;
    for (seg = 1; seg < len; seg += seg) {
    
    
        for (start = 0; start < len; start += seg + seg) {
    
    
            int low = start, mid = min(start + seg, len), high = min(start + seg + seg, len);
            int k = low;
            int start1 = low, end1 = mid;
            int start2 = mid, end2 = high;
            while (start1 < end1 && start2 < end2)
                b[k++] = a[start1] < a[start2] ? a[start1++] : a[start2++];
            while (start1 < end1)
                b[k++] = a[start1++];
            while (start2 < end2)
                b[k++] = a[start2++];
        }
        int* temp = a;
        a = b;
        b = temp;
    }
    if (a != arr) {
    
    
        int i;
        for (i = 0; i < len; i++)
            b[i] = a[i];
        b = a;
    }
    free(b);
}
int main()
{
    
    	
    int arr[] = {
    
     0, 22, 2, 33, 3, 1, 213, 5, 8, 9 };
    int sizeofnum=sizeof(arr)/sizeof(int);
	mergesort(arr,sizeofnum); 
	printarr(arr,sizeofnum);
	printf("%d",BinarySearch(arr,33));
}