2.3 关系运算符和逻辑表达式

￡神魔★判官ぃ 2022-05-20 01:07 221阅读 0赞

![70][]![70 1][]![70 2][]

![70 3][]

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; 
    	
    }

![70 4][]![70 5][]![70 6][]

![70 7][]

![70 8][]

第9页很重要

![70 9][]

![70 10][]

#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; 
    }

[70]: https://img-blog.csdn.net/20180710021908547?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbnlhbndlbm1lbmc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 1]: https://img-blog.csdn.net/20180710021918483?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbnlhbndlbm1lbmc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 2]: /images/20220520/cfa00bf26fb848559cea13f3ac84c0d4.png
[70 3]: /images/20220520/b04c55a5d62746ee815736e49d841977.png
[70 4]: https://img-blog.csdn.net/20180710021950598?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbnlhbndlbm1lbmc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 5]: https://img-blog.csdn.net/20180710022001387?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbnlhbndlbm1lbmc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 6]: /images/20220520/d20a08b1612f49d69645325cb135f871.png
[70 7]: /images/20220520/2bfbc1ff8347462cba80bb4fa80aed24.png
[70 8]: /images/20220520/8f0895c785274e92927bdb8b4f1c83ac.png
[70 9]: /images/20220520/525fa30300ba43c79ae481dc9cc296ed.png
[70 10]: /images/20220520/aa94a29478ef4891b6732bc3d0322aa4.png