C++深度解析教程笔记6-const常量引用数组

news/2024/5/19 15:16:46

C++深度解析教程笔记6

第12课 - const常量&引用数组
- 实验-const常量的判别
- 实验-引用作为数组元素
- 小结

本文学习自狄泰软件学院唐佐林老师的 C++深度解析教程，图片全部来源于课程PPT，仅用于个人学习记录

第12课 - const常量&引用数组

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实验-const常量的判别

#include <stdio.h>int main()
{const int x = 1;//在符号表，是常量const int& rx = x;//rx是x的别名，对应为x分配的内存空间，rx是只读变量int& nrx = const_cast<int&>(rx);//去除只读属性，目标类型只能是指针或者引用nrx = 5;printf("x = %d\n", x);printf("rx = %d\n", rx);printf("nrx = %d\n", nrx);//三个变量地址是一样的printf("&x = %p\n", &x);printf("&rx = %p\n", &rx);printf("&nrx = %p\n", &nrx);//可变的volatile const int y = 2;//2没放符号表，放在内存里int* p = const_cast<int*>(&y);//目标类型指针*p = 6;//修改指针指向的值printf("y = %d\n", y);//y改变了，证明了volatile修饰的变量放到了内存里printf("p = %p\n", p);//y的地址const int z = y;//z是只读变量p = const_cast<int*>(&z);*p = 7;printf("z = %d\n", z);//变化了，说明了使用变量初始化的const常量是只读变量printf("p = %p\n", p);char c = 'c';char& rc = c;const int& trc = c;//const int &  <---  char  类型不同的引用会生成新的只读变量，跟c毫无关系rc = 'a';//更改引用 的值printf("c = %c\n", c);printf("rc = %c\n", rc);printf("trc = %c\n", trc);printf("&c = %p\n", &c);printf("&rc = %p\n", &rc);printf("&trc = %p\n", &trc);return 0;
}
/*
x = 1
rx = 5
nrx = 5
&x = 0060FEE4
&rx = 0060FEE4
&nrx = 0060FEE4
y = 6
p = 0060FEE0
z = 7
p = 0060FEDC
c = a
rc = a
trc = c
&c = 0060FEDB
&rc = 0060FEDB
&trc = 0060FEE8*/

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实验-引用作为数组元素

#include <stdio.h>int a = 1;struct SV
{int& x;int& y;int& z;
};int main()
{int b = 2;int* pc = new int(3);SV sv = {a, b, *pc};int &array[]={a,b}; error: declaration of 'array' as array of references//int& array[] = {a, b, *pc}; // &array[1] - &array[0] = ?  Expected ==> 4
// error: declaration of 'array' as array of referencesprintf("&sv.x = %p\n", &sv.x);printf("&sv.y = %p\n", &sv.y);printf("&sv.z = %p\n", &sv.z);
//&sv.x = 0000000000403010
//&sv.y = 000000000061FE14
//&sv.z = 0000000000DA6E90delete pc;return 0;
}