转自：

http://blog.csdn.net/sxhelijian/article/details/15026159

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示例代码：

#include <iostream>
using namespace std;
const double pi=3.1415926;
int main( )
{
    float r,a;
    cout<<"输入半径："<<endl;
    cin>>r;
    a=pi*r*r;
    cout<<"输出面积：";
    cout<<a<<endl;
    return 0;
}

float volume(float h,float r)
{
    return pi*r*r*h;
}

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实践代码：

#include <iostream>
using namespace std;
const double pi=3.1415926;
int main( )
{
    int a;
    cout<<"请输入一个数："<<endl;
    cin>>a;
    if(a = 2)
        cout<<"你2了。";
    else
        cout<<"你不2。";
    return 0;
}

 

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示例代码：

#include <iostream>
using namespace std;
const double pi=3.1415926;
float area(float r);
int main( )
{
    float r1,a1;
    cin>>r1;
    a1=area(r1);
    cout<<a1<<endl;
    return 0;
}
float area(float r)
{
    float a;
    a = pi*r*r;
    return a;
}

 

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实践代码：

#include <iostream>
using namespace std;
float max(float x, float y);
int main ()
{
    float a,b,c;
    cin>>a>>b;
    c=max(a, b) ;
    cout<<"The max is "<<c<<endl;
    return 0;
}
float max(float x, float y)
{
    float z;
    z=(x<y)? x : y ;
    return  z;
}

 

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示例代码：

#include<iostream>
#include<cmath>
using namespace std;
int max(int,int);
int main( )
{
    int m,a,b;
    a=100;
    b=200;
    m=max(a,b);
    cout<<"最大:"<<m<<endl;
    return 0;
}
int max(int x,int y)
{
    int z;
    if(x>y)
        z=x;
    else
        z=y;
    return z;
}

 

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实践代码：

#include <iostream>
using namespace std;
float max(float x, float y);
int main ()
{
    float a,b,c;
    cin>>a>>b;
    c=max(a, b) ;
    cout<<"The max is "<<c<<endl;
    return 0;
}
float max(float x, float y)
{
    float z;
    z=(x<y)? x : y ;
    return  z;
}

 

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