(经典) K&R的名著<<C程序设计语言>>二分查找

#include<stdio.h>

//查找成功则返回所在下标否则返回-1

int binsearch(int A[], int n,int a)

{

   int low, high, mid;

   low = ;

   high = n -;

   while ( low <= high) {    /// 这里必须是 <=

        mid = (low+high) / 2;

        if (A[mid] == a)

           return mid;

        else if(A[mid]<a)

           low = mid +;

        else

           high=mid-;

    }

   return -;

}

int main()

{   int a[]={,,,,};

    printf("%d",binsearch(a,,));

}

//二分查找,递归算法

#include <iostream>

#include<stdio.h>

using namespace std;

int binSearch(int a[],int low,int high,int b)

{

    int mid = (high-low)/;

    if(a[mid] == b) return mid;

    if(a[mid] > b)  binSearch(a,low,mid-,b);

    if(a[mid] < b)  binSearch(a,mid+,high,b);

}

int main()

{   int a[] = {,,,,}; int yy;

    yy = binSearch(a,,,);

    printf("%d",yy);

    return ;

}