C++ (实验一)
实验结论
2-28 实现一个简单的菜单程序
（1）if
1 #include <iostream> 2 using namespace std; 3 4 int main(){ 5 char control; 6 cout<<"Menu: A(dd) D(elect) S(ort) Q(uit),select one:"; 7 cin>>control; 8 while(control!='Q'){ 9 if (control=='A') 10 cout<<"Data has been added"<<endl; 11 else if (control=='D') 12 cout<<"Data has been deleted"<<endl; 13 else if (control=='S') 14 cout<<"Data has been sorted"<<endl; 15 else 16 cout<<"Input error"<<endl; 17 cout<<"Menu: A(dd) D(elete) S(ort) Q(uit), Select one:"; 18 cin>>control;} 19 cout<<"Program end"<<endl; 20 return 0; 21 }
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（2）switch
1 #include <iostream> 2 using namespace std; 3 4 int main() { 5 char control; 6 cout<<"Menu: A(dd) D(elect) S(ort) Q(uit),select one:"; 7 cin>>control; 8 while(control!='Q'){ 9 switch (control) { 10 case 'A': 11 cout<<"Data has been added"<<endl; break; 12 case 'D': 13 cout<<"Data has been deleted"<<endl; break; 14 case 'S': 15 cout<<"Data has been sorted"<<endl; break; 16 default : 17 cout<<"Input error"<<endl; 18 } 19 cout<<"Menu: A(dd) D(elete) S(ort) Q(uit), Select one:"; 20 cin>>control;} 21 cout<<"Program end"<<endl; 22 return 0; 23 }
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2-29 穷举法找1～100间的质数
（1）while
1 #include <iostream> 2 #include <iomanip> 3 #include <cmath> 4 using namespace std; 5 6 int main(){ 7 int i,j,n,f; 8 n=0; 9 i=2; 10 while(i<=100) 11 {f=1; 12 j=2; 13 while(j<=sqrt(i)){ 14 if(i%j==0) 15 {f=0; 16 break;} 17 j++;} 18 if(f==1) 19 {cout<<setw(5)<<i; 20 n++; 21 if(n%5==0) 22 cout<<endl;} 23 i++;} 24 cout<<endl; 25 return 0; 26 }
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（2）do...while
1 #include <iostream> 2 #include <iomanip> 3 #include <cmath> 4 using namespace std; 5 6 int main(){ 7 int i,j,n,f; 8 n=1; 9 i=2; 10 cout<<setw(5)<<i; 11 do{ 12 f=1; 13 j=2; 14 do 15 { if(i%j==0) 16 {f=0; 17 break;} 18 j++; 19 }while(j<=sqrt(i)); 20 if(f==1) 21 {cout<<setw(5)<<i; 22 n++; 23 if(n%5==0) 24 cout<<endl;} 25 i++;}while(i<=100); 26 cout<<endl; 27 return 0; 28 }
（3）for
1 #include <iostream> 2 #include <iomanip> 3 #include <cmath> 4 using namespace std; 5 6 int main(){ 7 int i,j,n,f; 8 n=0; 9 for(i=2;i<=100;i++) 10 {f=1; 11 for(j=2;j<=sqrt(i);j++) 12 if(i%j==0) 13 {f=0; 14 break;} 15 if(f==1) 16 {cout<<setw(5)<<i; 17 n++; 18 if(n%5==0) 19 cout<<endl;} 20 } 21 cout<<endl; 22 return 0; 23 }
2-32 在1～100内用户猜数字
（1）while
1 #include <iostream> 2 #include <cstdlib> 3 using namespace std; 4 5 int main(){ 6 int number; 7 unsigned seed; 8 cout<<"please enter an arbitrary number from 1 to 100 :"; 9 cin>>number; 10 srand(number); 11 seed=rand()%100; 12 while(number!=seed) 13 {if(number<seed) 14 cout<<"The answer is bigger than the input number"<<endl; 15 else 16 cout<<"The answer is smaller than the input number"<<endl; 17 cout<<"please enter an arbitrary number:"; 18 cin>>number; 19 } 20 cout<<"you are right!"<<endl; 21 return 0; 22 }
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（2）do...while
1 #include <iostream> 2 using namespace std; 3 4 int main(){ 5 int number; 6 int answer=44; 7 do{ 8 cout<<"please enter an arbitrary number from 1 to 100 :"; 9 cin>>number; 10 {if(number<answer) 11 cout<<"The answer is bigger than the input number"<<endl; 12 else if(number>answer) 13 cout<<"The answer is smaller than the input number"<<endl;} 14 }while(number!=answer); 15 cout<<"you are right!"<<endl; 16 return 0; 17 }
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2-34 5种颜色球中抽3个不同颜色的球
1 #include <iostream> 2 using namespace std; 3 4 int main(){ 5 int i,j,k,total=0; 6 for(i=1;i<=5;i++) 7 for(j=i+1;j<=5;j++) 8 for(k=j+1;k<=5;k++) 9 total++; 10 cout<<total<<endl; 11 return 0; 12 }
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实验总结与体会
- break和continue只能用在switch或是循环语句中。
- 注意C++与C的一些函数使用的差异，如#include<math.h>(c中)，#include<cmath>(C++中)，abs与fabs等。
- 本次实验熟悉了C++的数据输入与输出与一些基础的算法。
- 随机数的运用是薄弱点，还需深入了解相关知识。
