20140717 二分查找

二分查找的代码

.  

int bfind(int* a,int len,int val) 

{  

    int m = len/2; 
    int l = 0; 
    int r = len;  
    while(l!=m && r!= m) 
    {  
        if(a[m] > val) 
        {  
            r = m;  
            m = (m+l)/2; 
        }  

        else if(a[m] < val) 
        {  
            l = m;  
            m = (m+r)/2; 
        } 
        else  
            return m; 
    }  
    return -1;   //没有找到

}