C++ const关键字分析详解

#include <stdio.h>
//代码1
void test1()
{
	int n = 10;
	int m = 20;
	int *p = &n;
	*p = 20;//ok
	p = &m; //ok
}
void test2()
{
	//代码2
	int n = 10;
	int m = 20;
	const int* p = &n;
	*p = 20;//err
	p = &m; //ok
}
void test3()
{
	int n = 10;
	int m = 20;
	int *const p = &n;
	*p = 20; //ok
	p = &m; //err
}
int main()
{
	//测试无cosnt的
	test1();
	//测试const放在*的左边
	test2();
	//测试const放在*的右边
	test3();
	return 0;
}

void TestConst()
{
    const int a = 10; 
    int*pa =(int*)&a;
    *pa = 100;
    cout<<a<<endl;//10
    //但是a的值已经是100原因:在编译阶段，编译器已经将a用10替换了 
    cout <<*pa <<endl; // 100
}