C 语言学习

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cmath>
using namespace std;

void fun(int x,int *y){
    int a=4 ;
    *y=x+a;
    x=*y;
}

void main(void){
    int a=2,b=3,*c=&b;
    fun(a,c);
    cout<<a<<endl;
    cout<<b<<endl;
    cout<<*c<<endl;
    system("pause");
}

 

 

 

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cmath>
using namespace std;

union st{
   int a[2];
   int b[2];
   int c;
};



int main(){
    union st y;
    y.a[0]=10; 
    y.b[1]=20;
    y.c=30;
    cout<<y.a[0]<<endl;
    cout<<y.a[1]<<endl;
    system("pause");
    return 0;
}

 30 ,20

 

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cmath>
using namespace std;

union out{
  int a [2];
  struct{
   int b;
   int c;
  }in;
  int d;
};



int main(){
        union out e;
	e.in.b=1;
	e.in.c=2;
	e.d=3;
	for(int i=0;i<2;i++){
	cout<<e.a[i]<<endl;
	}
	system("pause");
	return 0;
}

  

 3,2

 

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cmath>
using namespace std;

int a=1;
int sub(int c,int d){
  static int m=2,n=5;
  cout<<m<<'\t'<<n<<'\t'<<endl;
  a=++a;
  c=m++;
  d=n++;
  return c+d;
}

int main(){
   int m=1,n=2,f;
   f=sub(m,n);
   cout<<a<<'\t'<<f<<endl;
   f=sub(m,n);
   cout<<a<<'\t'<<f<<endl;
   system("pause");
   return 0;
}

 

  2    5

  2    7

  3    6

  3    9

 

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cmath>
using namespace std;

void test1(int *a1){
 a1=new int(5);
 cout<<"*a1="<<*a1<<endl;
}

void test2(int * &a2){
 a2=new int(5);
 cout<<"*a2="<<*a2<<endl;
}


int main(){
   int *p=new int(1);
   test1(p);
   cout<<"test1:*p1="<<*p<<endl;
   
   test2(p);
   cout<<"test2:*p2="<<*p<<endl;

   system("pause");
   return 0;
}

 

*a1= 5
test1: *p1= 1
*a2= 5
test2: *p2= 5

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cmath>
using namespace std;

class T{
public:
	   T(int x){a=x;b+=x;}
       static void display(T c){
	   cout<<"a="<<c.a<<'\t'<<"b="<<c.b<<endl;
	   }
private:
	int a;
	static int b;
};

int T::b=5;


int main(){
   T A(3),B(5);
   T::display(A);
   T::display(B);

   system("pause");
   return 0;
}

 

a=3      b=13
a=5      b=13

 

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cmath>
using namespace std;

class Base1{
public:
	Base1(int i){
	cout<<"调用基类Base1的构造函数："<<i<<endl;
	}
};

class Base2{
public:
	Base2(int j){
	cout<<"调用基类Base2的构造函数："<<j<<endl;
	}
};

class A:public Base2,public Base1{
public:
	A(int a,int b,int c,int d):Base2(b),Base1(c),b2(a),b1(d){
	cout<<"调用派生类A的构造函数:"<<a+b+c+d<<endl;
	}
private:
	Base1 b1;
	Base2 b2;

	
};

void main(){
   A obj( 1, 2, 3, 4 );
   system("pause");

}

 

调用基类BASE2的构造函数:2
调用基类BASE1的构造函数:3
调用基类BASE1的构造函数:4
调用基类BASE2构造函数:1
调用派生类A的构造函数:10