C++基础知识实例解析（一）

#include <iostream>
using namespace std;
int division(int x){ return x/2; }
long division(long x){ return x/2; }
float division(float x){ return x/2; }
double division(double x){ return x/2; }
int main()
{
   int a; long b; float c; double d;
 cout<<"input a,b,c,d:"<<endl; cin>>a>>b>>c>>d;
 if(a!=0) cout<<a<<"/2="<<division(a)<<endl;
 else cout<<"input error!"<<endl;
   if(b!=0) cout<<b<<"/2="<<division(b)<<endl;
 else cout<<"input error!"<<endl;
 if(c!=0) cout<<c<<"/2="<<division(c)<<endl;
 else cout<<"input error!"<<endl;
   if(d!=0) cout<<d<<"/2="<<division(d)<<endl;
   else cout<<"input error!"<<endl;
 return 0;
}

#include <iostream>
using namespace std;
void swap(int &a,int &b)
{ int t; t=a; a=b; b=t;}
void max(int a,int b,int c,int &maxnum,int &minnum)
{
 if(a<=b) swap(a,b);
 if(a<=c) swap(a,c);
 if(b<=c) swap(b,c);
   maxnum=a; minnum=c;
}
int main()
{
 int a,b,c,maxnum,minnum;
 cout<<"input a,b,c:"; cin>>a>>b>>c;
 max(a,b,c,maxnum,minnum);
   cout<<"maxnum="<<maxnum<<endl;
 cout<<"minnum="<<minnum<<endl;
 return 0;
}

#include <iostream>
using namespace std;
float volumn(float a=10,float b=10,float c=10);
int main()
{
   float a,b,c;
 cout<<"没有实际参数值时，volumn="<<volumn()<<endl;
 cout<<"input a,b,c:"; cin>>a>>b>>c;
   cout<<"有实际参数值时，volumn="<<volumn(a,b,c)<<endl;
 return 0;
}
float volumn(float a,float b,float c)
{ return a*b*c;  }

#include <iostream>
using namespace std;
float avg(float,float);
float avg(float,float,float);
float avg(float,float,float,float);
int main()
{
 cout<<"The first student:"<<avg(80.0f,70.2f)<<endl;
 cout<<"The second student:"<<avg(80.1f,78.1f,12.3f)<<endl;
 cout<<"The third student:"<<avg(45.6f,90.1f,78.6f)<<endl;
 return 0;
}
float avg(float x,float y) { return (x+y)/2.0;  }
float avg(float a,float b,float c) { return (a+b+c)/3; }
float avg(float a,float b,float c,float d){ return (a+b+c+d)/4; }