2.3 关系运算符和逻辑表达式

true等价于非0整型值，通常为1.

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
	int n1 = 4, n2 = 5, n3;
	n3 = ( n1 > n2);//(n1>n2)为false，n3=0
	cout << n3 << "," ;//0,
	n3 = (n1 < n2);//(n1<n2)为true，n3为非零值;
	cout << n3 << ",";//1,
	n3 = (n1 == 4);//n1==4为true，n3为非零值；
	cout << n3 << ","; //1,
	n3 = (n1 != 4);//n3=0;
	cout << n3 << ",";
	n3 = (n1==5);//n1==5为false ,n3=0;
	cout << n3;
	return 0; 
	
}

第9页很重要

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
	int a = 0, b = 1;
	bool n = (a ++) && (b ++);//(a ++)返回值为0，因此(b ++)不用再计算了,但a的值为1 
	cout << a << "," << b << endl;//1,1
	n = a ++ && b++ ;//a ++ 返回值为1，因此还要计算 b++，a=2，b=2 
	cout << a << "," << b << endl;//2,2
	n = a ++ || b++;//a ++返回值为2，为true，a变为3，因此b++不用再计算了 
	cout << a << "," << b << endl;//3,2
	return 0; 
}