visual c++ 2012入门经典 练习（第五章）

（一）求阶乘：

#include <iostream>

#include <iomanip>

using std::cin;

using std::cout;

using std::endl;

using std::setw;

int fact(int n);

int main(int argc,char* argv[]){
int a;
int result;
cout<<"输入a值：";
cin>>a;
try{
result=fact(a);
if(result==0)
throw "输入的值有误";
cout<<"a的阶乘是："<<a<<"!="<<result<<endl;
//cout<<"5的阶乘是："<<"5!="<<result<<endl;
}
catch(const char message[]){
cout<<message<<endl;

}

}

int fact(int n){
int result;
if(n>0)
return result=n*fact(n-1);
else if(n<0){
cout<<"请输入正值"<<endl;
return 0;
}
else
return 1;
//return result;
}

（二）指针传递交换值

#include <iostream>

#include <iomanip>

using std::cin;

using std::cout;

using std::endl;

using std::setw;

int ex_num(int* a,int* b);

int main(int argc,char* argv[]){
int a_num(5);
int b_num(6);
int* pa(&a_num);
int* pb(&b_num);
ex_num(pa,pb);
//ex_num(&a_num,&b_num);
cout<<"a_num="<<a_num<<"；"<<"b_num="<<b_num<<endl;

}

int ex_num(int* a,int* b){
int t;
t=*a;
*a=*b;
*b=t;
return 0;

}

（三）三角函数

#include <iostream>

#include <iomanip>

#include <cmath>

using std::cin;

using std::cout;

using std::endl;

using std::setw;

double sind(double angle);

double cosd(double angle);

double tand(double angle);

#define PI 3.1415925

int main(int argc,char* argv[]){
double angle_a;
double angle_b;
double angle_c;

//cout<<"sin(90)="<<sin(90)<<endl;
cout<<"请输入角度："<<endl;
cin>>angle_a;
cin>>angle_b;
cin>>angle_c;
cout<<"sind("<<angle_a<<")="<<sind(angle_a)<<endl;
cout<<"cosd("<<angle_b<<")="<<cosd(angle_b)<<endl;
cout<<"tand("<<angle_c<<")="<<tand(angle_c)<<endl;

}

double sind(double angle){
return sin(angle/180.0*PI);

}

double cosd(double angle){
return cos(angle/180.0*PI);

}

double tand(double angle){
return tan(angle/180.0*PI);

}