C基础第26课--指针的本质分析

学习自狄泰软件学院唐佐林老师C语言课程，文章中图片取自老师的PPT，仅用于个人笔记。

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实验1

#include <stdio.h>

int main()
{
    int i = 0;
    int* pI;
    char* pC;
    float* pF;
    
    pI = &i;
    
    *pI = 10;
    
    printf("%p, %p, %d\n", pI, &i, i);
    printf("%d, %d, %p\n", sizeof(int*), sizeof(pI), &pI);
    printf("%d, %d, %p\n", sizeof(char*), sizeof(pC), &pC);
    printf("%d, %d, %p\n", sizeof(float*), sizeof(pF), &pF);
    
    return 0;
}





mhr@ubuntu:~/work/C$ 
mhr@ubuntu:~/work/C$ ./a.out 
0x7ffe8ce0710c, 0x7ffe8ce0710c, 10
8, 8, 0x7ffe8ce07110
8, 8, 0x7ffe8ce07118
8, 8, 0x7ffe8ce07120
mhr@ubuntu:~/work/C$ 

注意： 函数调用时候实参将复制给形参！！！

实验2

#include <stdio.h>

int swap(int* a, int* b)
{
    int c = *a;
    
    *a = *b;
    
    *b = c;
}

int main()
{
    int aa = 1;
    int bb = 2;
    
    printf("aa = %d, bb = %d\n", aa, bb);
    
    swap(&aa, &bb);
    
    printf("aa = %d, bb = %d\n", aa, bb);
    
    return 0;
}


mhr@ubuntu:~/work/C$ gcc 26-2.c
mhr@ubuntu:~/work/C$ 
mhr@ubuntu:~/work/C$ 
mhr@ubuntu:~/work/C$ ./a.out 
aa = 1, bb = 2
aa = 2, bb = 1
mhr@ubuntu:~/work/C$ 

实验3

#include <stdio.h>

int main()
{
    int i = 0;
    
    const int* p1 = &i;
    int const* p2 = &i;
    int* const p3 = &i;
    const int* const p4 = &i;
    
    *p1 = 1;    // compile error
    p1 = NULL;  // ok
    
    *p2 = 2;    // compile error
    p2 = NULL;  // ok
    
    *p3 = 3;    // ok
    p3 = NULL;  // compile error
    
    *p4 = 4;    // compile error
    p4 = NULL;  // compile error
    
    return 0;
}

来源：CSDN

作者：奶牛养殖场小马

链接：https://blog.csdn.net/LinuxArmbiggod/article/details/104050485