C语言进阶课程学习记录- 函数与宏分析

news2024/9/20 14:42:00

C语言进阶课程学习记录- 函数与宏分析

- 实验-宏和函数
- 实验-宏的副作用
- 实验-宏的妙用
- 小结

本文学习自狄泰软件学院唐佐林老师的 C语言进阶课程，图片全部来源于课程PPT，仅用于个人学习记录

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实验-宏和函数

#include <stdio.h>

#define RESET(p, len)          \
    while( len > 0 )           \
        ((char*)p)[--len] = 0

void reset(void* p, int len)
{
    while( len > 0 )
        ((char*)p)[--len] = 0;
}

int main()
{
    int array[] = {1, 2, 3, 4, 5};
    int len = sizeof(array);
    int i = 0;

    for(i=0; i<5; i++)
    {
        printf("array[%d] = %d\n", i, array[i]);
    }

    //reset(array, len);//case1

    RESET(array, len);//case2
    for(i=0; i<5; i++)
    {
        printf("array[%d] = %d\n", i, array[i]);
    }


    return 0;
}



    /*
    output:
array[0] = 1
array[1] = 2
array[2] = 3
array[3] = 4
array[4] = 5
array[0] = 0
array[1] = 0
array[2] = 0
array[3] = 0
array[4] = 0
    */

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实验-宏的副作用

#include <stdio.h>

#define _ADD_(a, b) a + b
#define _MUL_(a, b) a * b
#define _MIN_(a, b) ((a) < (b) ? (a) : (b))

int main()
{
    int i = 1;
    int j = 10;

    printf("%d\n", _MUL_(_ADD_(1, 2), _ADD_(3, 4)));
    printf("%d\n", _MIN_(i++, j));
     //printf("%d\n", 1 + 2 * 3 + 4);
    //printf("%d\n", ((i++) < (j) ? (i++) : (j)));

    return 0;
}



    /*
    output:
11
2
    */

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实验-宏的妙用

#include <stdio.h>
#include <malloc.h>

#define MALLOC(type, x)   (type*)malloc(sizeof(type)*x)
#define FREE(p)           (free(p), p=NULL)

#define LOG_INT(i)        printf("%s = %d\n", #i, i)
#define LOG_CHAR(c)       printf("%s = %c\n", #c, c)
#define LOG_FLOAT(f)      printf("%s = %f\n", #f, f)
#define LOG_POINTER(p)    printf("%s = %p\n", #p, p)
#define LOG_STRING(s)     printf("%s = %s\n", #s, s)

#define FOREACH(i, n)     while(1) { int i = 0, l = n; for(i=0; i < l; i++)
#define BEGIN             {
#define END               } break; }

int main()
{
    int* pi = MALLOC(int, 5);
    char* str = "D.T.Software";

    LOG_STRING(str);

    LOG_POINTER(pi);

    FOREACH(k, 5)
    BEGIN
        pi[k] = k + 1;
    END

    FOREACH(n, 5)
    BEGIN
        int value = pi[n];
        LOG_INT(value);
    END

    FREE(pi);

    LOG_POINTER(pi);

    return 0;
}



    /*
    output:
str = D.T.Software
pi = 00702D28
value = 1
value = 2
value = 3
value = 4
value = 5
pi = 00000000
    */