第七章1-3题

#include<iostream>double avg(double x , double y);int main(){ using namespace std; int x = 0; int y = 0; while(1) { cout<<"请输入第一个数:"; cin>>x; if(!cin) break; cout<<"请输入第二个数:"; cin>>y; if(!cin) break; //首先确保输入的是double if(x ==0 or y ==0) break; //然后确保输入的2个数都不为0 cout<<"调和平均数:"<<avg(x,y)<<endl; } cout<<"程序结束"; return 0;}double avg(double x , double y){ return (2*x*y)/(x+y);}

#include<iostream>int fillArray(double golf[] , int limit);void showArray(const double golf[] , int limit);void avgArray(const double golf[] , int limit);const int MAX = 10;using namespace std;int main(){ int SIZE = 0; double golf[MAX]; SIZE = fillArray(golf,MAX); showArray(golf,SIZE); avgArray(golf,SIZE); return 0;}int fillArray(double golf[] , int limit){ double achievement = 0; int size = 0; golf[0] = 0; //先把数组的第一个数填充位0，如果手动输入的时候第一个数字输入非法可以避免段错误 for(int i = 0 ; i < limit ; ++i) { cout<<"请输入第"<<i+1<<"个成绩"; cin>>achievement; if(!cin) { cout<<"输入结束\n"; break; } if(achievement < 0 or achievement > 100) //不会高尔夫，假设高尔夫的成绩位0-100直接的double.. { cout<<"输入结束\n"; break; } golf[i] = achievement; ++size; } return size;}void showArray(const double golf[] , int limit){ if(limit == 0) cout<<"无效的成绩.\n"; for(int i = 0 ; i < limit ; ++i) cout<<"第"<<i+1<<"个高尔夫成绩为"<<golf[i]<<endl;}void avgArray(const double golf[] , int limit){ double sue = 0; for(int i = 0 ; i < limit ; ++i) sue = sue + golf[i]; if(limit != 0) sue = sue/limit; cout<<"高尔夫的平均成绩为"<<sue;}

#include<iostream>using namespace std;struct box{ char maker[40]; float height; float width; float lenght; float volume;};void showBox(box myBox);void countVolume(box* myBox);int main(){ box boxes = {"Volume",10.1,20.2,30.3,0}; cout<<"立方体数据:\n"; showBox(boxes); countVolume(&boxes); cout<<"立方体数据已经更改:\n"; showBox(boxes); return 0;}void showBox(box myBox){ cout<<"名称:"<<myBox.maker<<endl; cout<<"高度:"<<myBox.height<<endl; cout<<"宽度:"<<myBox.width<<endl; cout<<"长度:"<<myBox.lenght<<endl; cout<<"体积:"<<myBox.volume<<endl;}void countVolume(box* myBox){ myBox->volume = (myBox->height) * (myBox->width) * (myBox->lenght);}