二分查找

二分查找，元素存在则返回元素，不存在则返回-1

代码：

int BinarySearch( int A[],int n,int x )

{

int left=0;

int right =n-1;

while(left<=right)

{

int middle =(left+right)/2;

if((A[middle])==x )return A[middle];

if (A[middle]<x) left=middle+1;

else right=middle -1;

}

return -1;

}

int main()

{ int s[10]={1,2,3,4,5,6,7,8,9,10};

int k=BinarySearch(s,10,5);

cout<<k<<endl;

return 0;

}