readdir+回调函数实现目录遍历（V0.1）

需求：
   使用回调函数遍历指定目录。

实现：
    函数实现处，橙色部分为重点，即路径变量控制：
 点击(此处)折叠或打开

/********************************************************
*filename    : scan.c
*descriptor    : source file - scan the directory that given
*autor        : Rocky
*date        : 2017-06-22
********************************************************/

#include "scan.h"

#ifdef _MAN_READDIR
//On Linux, the dirent structure is defined as follows:

struct dirent {
    ino_t          d_ino; /* inode number */
    off_t          d_off; /* not an offset; see NOTES */
    unsigned short d_reclen; /* length of this record */
    unsigned char  d_type; /* type of file; not supported
                                 by all filesystem types */
    char           d_name[256]; /* filename */
};
/*
d_type:

DT_BLK      This is a block device.
DT_CHR      This is a character device.
DT_DIR      This is a directory.
DT_FIFO     This is a named pipe (FIFO).
DT_LNK      This is a symbolic link.
DT_REG      This is a regular file.
DT_SOCK     This is a UNIX domain socket.
DT_UNKNOWN  The file type is unknown.
*/
#endif

int start_scan(const char *dirname)
{
    DIR *dir_ptr;
    struct dirent *ptr;
    char deeper_dir[PATH_MAX] = {0};

    dir_ptr = opendir(dirname);
    if (NULL == dir_ptr)
    {
        perror("opendir error");
        return -1;
    }

    while ((ptr = readdir(dir_ptr)))
    {
        /* ignore the "." nad ".." */
        if (!strcmp(ptr->d_name, ".") || !(strcmp(ptr->d_name, "..")))
            continue;

        printf("name is %s\n", ptr->d_name);
        if (DT_REG == ptr->d_type)
        {
            printf("+++++ I am a regule file\n");
        }
        else if (DT_DIR == ptr->d_type)
        {
            printf("----- I am a directory\n");

            strcpy(deeper_dir, dirname);
            strcat(deeper_dir, "/");
            strcat(deeper_dir, ptr->d_name);

            start_scan(deeper_dir);
        }
    }

    closedir(dir_ptr);

    return 0;
}

头文件定义：

/********************************************************
*filename    : scan.h
*descriptor    : head file - scan the directory that given
*autor        : Rocky
*date        : 2017-06-22
********************************************************/

#ifndef _SCAN_H_
#define _SCAN_H_

#include <stdio.h>
#include <dirent.h>
#include <string.h>
#include <sys/types.h>

#ifndef PATH_MAX
    #define PATH_MAX 256
#endif //PATH_MAX

int start_scan(const char *dirname);

#endif // _SCAN_H_

/**********************************************************
*filename    : main.c
*autor        : Rocky
*date        : 2017-06-22
************************************************************/

#include "scan.h"

int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        printf("Usage : %s dirname\n", argv[0]);
        return -1;
    }

    printf("dirname is %s\n", argv[1]);
    start_scan(argv[1]);

    return 0;
}

工程管理（简单管理，日后还需深入学习makefile，以便进行高级的项目管理）：

CC=gcc

target=main

CSOURCE:=
CSOURCE+=main.c
CSOURCE+=scan.c

CFLAGS:=
CFLAGS+=-Wall

$(target):$(CSOURCE)
$(CC) -o $@ $^ $(CFLAGS)

clean:
rm $(target)

运行结果：
    

总结：
     实现了需要的功能。因为平时逻辑思维能力较差（脑子转不过来弯），所以在工作中遇到这类问题时往往反应迟钝，耽误大量宝贵时间。日后多加强这方面的练习，多做这种小练习，让大脑转动起来。