一些C++的小程序（一）

输出hello word

#include <iostream>using namespace std;int main(){cout << "hello，word\n";    return 0;}

查找int的空间大小

#include <iostream>using namespace std;int main(){cout << "The size of an int is :\t\t" << sizeof(int) << "bytes.\n";    return 0;}

定义枚举类型，输出比赛结果

#include <iostream>using namespace std;enum GameResult {WIN,LOSE,TIE,CANCEL};int main(){GameResult result;enum GameResult omit = CANCEL;for (int count = WIN; count <= CANCEL; count++) {result = GameResult(count);if (result == omit)cout << "The game was cancelled" << endl;else {cout << "The game was played";if (result == WIN) cout << "and we won";if (result == LOSE) cout << "and we lost";cout << endl;}}    return 0;}

使用do-while语句，求自然数1-10之和

#include <iostream>using namespace std;int main(){int i = 1, sum = 0;do { sum += 1;i++;} while (i <= 10);cout << "sum=" << sum << endl;    return 0;}

//计算圆形，正方形，矩形的面积，运行时先提示用户选择图形类型，
//然后对图形要求用户输入半径值，对长方形要求用户输入长和宽的值，
//对正方形要求用户输入边长的值，计算面积的值然后显示出来。

#include <iostream>using namespace std;const float PI = 3.1416;int main(){int iType;float radius, a, b, area;cout << "图形的类型为？（1-圆形 2-正方形 3-圆）:";cin >> iType;switch(iType){case 1:cout << "圆的半径：";cin >> radius;area = PI*radius*radius;cout << "面积为：" << area << endl;break;case 2:cout << "矩形的长为：";cin >> a; cout << "矩形的宽为：";cin >> b;area = a*b;cout << "面积为：" << area << endl;break;case 3:cout << "正方形的半径：";cin >> a;area = a*a;cout << "面积为：" << area << endl;break;default:cout << "不是合法输入值"<<endl;}    return 0;}

//声明一个表示时间的结构体
//可以精确表示年月日小时分秒
//提示用户输入然后完全显示（利用struct结构体)

#include "iostream"using namespace std;struct MytimeStruce{unsigned int year;unsigned int month;unsigned int day;unsigned int hour;unsigned int min;unsigned int sec;};int main(){MytimeStruce mytime = { 2017,11,22,18,45,58 };cout << "please input year:" << endl;cin >> mytime.year;cout << "please input month:" << endl;cin >> mytime.month;cout << "please input day:" << endl;cin >> mytime.day;cout << "please input hour:" << endl;cin >> mytime.hour;cout << "please input min:" << endl;cin >> mytime.min;cout << "please input sec:" << endl;cin >> mytime.sec;cout << "the time is set to:" << mytime.year << "/";cout << mytime.month << "/";cout << mytime.day << " ";cout << mytime.hour << ":";cout << mytime.min << ":";cout << mytime.sec << endl;    return 0;}

//利用函数计算x的n次方

#include "iostream"using namespace std;double power(double x, int n) {double val = 1.0;while (n--)val *= x;return val;}int main(){double pow;pow = power(5, 2);cout << "5 to the power 2 is " << pow << endl;    return 0;}

//函数的嵌套
//输入两个数，求两个数的平方和

#include "iostream"using namespace std;int fun2(int m) {return m*m;}int fun1(int x, int y) {return fun2(x) + fun2(y);}int main(){int a, b;cout << "Please enter two integers(a and b):";cin >> a >> b;cout << "The sum of square of a and b :" << fun1(a, b) << endl;    return 0;}

//利用的函数的引用

//输入两个整数交换后输出

#include "iostream"using namespace std;void swap(int &a, int &b) {int t = a;a = b;b = t;}int main(){int x = 5, y = 10;cout << "x=" << x << "y=" << y <<endl;swap(x, y);cout << "x=" << x << "y=" << y <<endl;    return 0;}

//内联函数
//声明关键字inline
//计算圆的面积

#include "iostream"using namespace std;const double PI = 3.14159265358979;inline double calArea(double radius) {return PI*radius*radius;}int main(){double r = 3.0;double area = calArea(r);cout << area << endl;    return 0;}

//使用debug的 step into功能追踪到函数内部
//编写函数float Convert（float F）参数和返回值为float类型
//实现算法：C=(F-32)*5/9

#include "iostream"using namespace std;float Convert(float F){float C;C = (F - 32) * 5 / 9;return C;}int main(){float F;cout << "Please input the temperature in fahrenheit:\n";cin >> F;cout << "Conver the temperature in celsius:\n";cout << Convert(F);    return 0;}