Question

c++ 用二分法查数，出现问题了，求高手指点迷津？

#include<iostream>
#define size 5
using namespace std;
void main()
{
int i,j;
float t,a[size];
for(i=0;i<size;i++)
{
cout<<"a["<<i<<"]=";
cin>>a[i];
}
cout<<endl;

for(i=0;i<size-1;i++)
{
for(j=i+1;j<size;j++)
{
if(a[i]>a[j])
{
t=a[i];
a[i]=a[j];
a[j]=t;
}
}
}

for(i=0;i<size;i++)
{
cout<<"a["<<i<<"]=";
cout<<a[i]<<" ";
}
cout<<endl;

int value;
int found;
int low,mid,high;
cout<<"Enter the value of found: ";
cin>>found;
low=0;
found=0;
high=size-1;
while(low<=high)
{
mid=(low+high)/2;
if(value==a[mid])
{
found=1;
break;
}
else if(value<a[mid])high=mid-1;
else if(value>a[mid])low=mid+1;

if(found)cout<<"The value is: a["<<mid<<"]"<<endl;
}
if(found==0)cout<<"The value cann't find!"<<endl;
}

编译无错，排序也对，就是查不出想查的数，求高手点拨；

Answer 1

/*

36 25 41 58 97

a[0] = 36

a[1] = 25

a[2] = 41

a[3] = 58

a[4] = 97

a[0] = 25   a[1] = 36   a[2] = 41   a[3] = 58   a[4] = 97

Enter the value of found: 41

The value is: a[2]

Press any key to continue

*/

#include<iostream>
#define size 5
using namespace std;

void main() {
	int i,j;
	float t,a[size];
	for(i = 0;i < size;i++) {
		cin >> a[i]; // 先输入，后显示
		cout << "a[" << i << "] = " << a[i] << endl;
	}
	cout << endl;
	for(i = 0;i < size - 1;i++) {
		for(j = i + 1;j < size;j++) {
			if(a[i] > a[j]) {
				t = a[i];
				a[i] = a[j];
				a[j] = t;
			}
		}
	}
	for(i = 0;i < size;i++) {
		cout << "a[" << i << "] = " << a[i] << "   ";
	}
	cout << endl;
	int value;
	int found;
	int low,mid,high;
	cout << "Enter the value of found: ";
	cin >> value;
	low = 0;
	high = size - 1;
	while(low <= high) {
		mid = (low + high) / 2;
		if(value == a[mid])	{
			found = 1;
			break;
		}
		else if(value < a[mid]) high = mid - 1;
		else low = mid + 1;
	}
	if(found)cout << "The value is: a[" << mid << "]\n";
	else cout << "The value cann't find!\n";
}