opencv中批量读取图片并保存

痛定思痛。 2022-05-27 10:23 311阅读 0赞

之前一直在写python，突然要用C++，因为涉及到图像处理，需要批量读取并存储图片，这里对图片的批量处理代码做一下汇总：

**方法1：比较简单，唯一的要求就是文件夹下的图片名称是有规律的，比如1，2，3。**

#include "opencv2/opencv.hpp" 
    #include "iostream" 
    
    using namespace std;  
    using namespace cv;  
    
    #define NUM 100 //读取image的个数 
    int main()  
    {  
        Mat image;  
        string ImgName;  
        int n=1;  
        while(n<=NUM)   //100 
        {   
            ImgName="woman";  
            //int 转换string 
            stringstream ss;  
            string str;  
            ss<<n;  
            ss>>str;  
    
            ImgName=ImgName+" ("+str+")";    //图像文件明格式：ImgName(n) 
            ImgName = "D:\\Mycode\\imagebank\\woman\\" + ImgName+".png";  
            cout<<"处理："<<ImgName<<endl;  
            image= imread(ImgName);//读取图片 
            if(image.data ==0)  
            { printf("[error] 没有图片\n");}  
            n++;  
       }  
    
        waitKey(0);  
        system("pause");  
        return 4;  
    }

**方法二：需要一个 .txt文件存放文件中待读取图像的名称，每行为一条图像名。**

#include "opencv2/opencv.hpp" 
    #include "iostream" 
    #include <fstream> 
    using namespace std;  
    using namespace cv;  
    
    int main()  
    {  
        Mat image;  
        string ImgName;  
        ifstream fin("woman.txt");//打开原始样本图片文件列表 
        while(getline(fin,ImgName)) //一行一行读取文件列表 
        {    
          cout<<"处理："<<ImgName<<endl;  
          ImgName = "D:\\Mycode\\woman\\" + ImgName+".png";  
          image= imread(ImgName);//读取图片 
    
         if(image.data ==0)  
          {
       printf("[error] 没有图片\n");return -5;}  
        }  
            waitKey(0);   
    return 4;  
    }

**方法三：最简单，只需要一个“dirent.h”头文件便可以遍历指定文件夹的所有文件。**

#include "opencv2/opencv.hpp" 
    #include <fstream> 
    #include <iostream> 
    #include <string> 
    #include "dirent.h" 
    
    using namespace std;  
    using namespace cv;  
    
    int main()  
    {  
        DIR *dir;   
        struct dirent *entry;   
        if((dir=opendir("D:\\Mycode\\VS2010work\\10Image_cut\\Image_cut\\noperson"))==NULL)   
            printf( "Error opening \n ");   
        else {   
            while((entry=readdir(dir))!=NULL) {   
              cout<<entry->d_name<<endl;  
            }   
        }  
        closedir(dir);    
        system("pause");  
        return 0;  
    }

下面给出dirent.h头文件（文件要放到VS安装目录中的include文件夹下，我的路径为C:\\vs2015\\VC\\include）

/* * Dirent interface for Microsoft Visual Studio * Version 1.21 * * Copyright (C) 2006-2012 Toni Ronkko * This file is part of dirent. Dirent may be freely distributed * under the MIT license. For all details and documentation, see * https://github.com/tronkko/dirent * http://www.softagalleria.net/dirent.php * http://blog.csdn.net/thefinals/article/details/7174854 * https://zhidao.baidu.com/question/939784399849992372.html * http://blog.chinaunix.net/uid-27213819-id-3810699.html */  
    #ifndef DIRENT_H 
    #define DIRENT_H 
    
    /* * Define architecture flags so we don't need to include windows.h. * Avoiding windows.h makes it simpler to use windows sockets in conjunction * with dirent.h. */  
    #if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_IA64_) && !defined(_AMD64_) && defined(_M_IX86) 
    # define _X86_ 
    #endif 
    #if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_IA64_) && !defined(_AMD64_) && defined(_M_AMD64) 
    #define _AMD64_ 
    #endif 
    
    #include <stdio.h> 
    #include <stdarg.h> 
    #include <windef.h> 
    #include <winbase.h> 
    #include <wchar.h> 
    #include <string.h> 
    #include <stdlib.h> 
    #include <malloc.h> 
    #include <sys/types.h> 
    #include <sys/stat.h> 
    #include <errno.h> 
    
    /* Indicates that d_type field is available in dirent structure */  
    #define _DIRENT_HAVE_D_TYPE 
    
    /* Indicates that d_namlen field is available in dirent structure */  
    #define _DIRENT_HAVE_D_NAMLEN 
    
    /* Entries missing from MSVC 6.0 */  
    #if !defined(FILE_ATTRIBUTE_DEVICE) 
    # define FILE_ATTRIBUTE_DEVICE 0x40 
    #endif 
    
    /* File type and permission flags for stat(), general mask */  
    #if !defined(S_IFMT) 
    # define S_IFMT _S_IFMT 
    #endif 
    
    /* Directory bit */  
    #if !defined(S_IFDIR) 
    # define S_IFDIR _S_IFDIR 
    #endif 
    
    /* Character device bit */  
    #if !defined(S_IFCHR) 
    # define S_IFCHR _S_IFCHR 
    #endif 
    
    /* Pipe bit */  
    #if !defined(S_IFFIFO) 
    # define S_IFFIFO _S_IFFIFO 
    #endif 
    
    /* Regular file bit */  
    #if !defined(S_IFREG) 
    # define S_IFREG _S_IFREG 
    #endif 
    
    /* Read permission */  
    #if !defined(S_IREAD) 
    # define S_IREAD _S_IREAD 
    #endif 
    
    /* Write permission */  
    #if !defined(S_IWRITE) 
    # define S_IWRITE _S_IWRITE 
    #endif 
    
    /* Execute permission */  
    #if !defined(S_IEXEC) 
    # define S_IEXEC _S_IEXEC 
    #endif 
    
    /* Pipe */  
    #if !defined(S_IFIFO) 
    # define S_IFIFO _S_IFIFO 
    #endif 
    
    /* Block device */  
    #if !defined(S_IFBLK) 
    # define S_IFBLK 0 
    #endif 
    
    /* Link */  
    #if !defined(S_IFLNK) 
    # define S_IFLNK 0 
    #endif 
    
    /* Socket */  
    #if !defined(S_IFSOCK) 
    # define S_IFSOCK 0 
    #endif 
    
    /* Read user permission */  
    #if !defined(S_IRUSR) 
    # define S_IRUSR S_IREAD 
    #endif 
    
    /* Write user permission */  
    #if !defined(S_IWUSR) 
    # define S_IWUSR S_IWRITE 
    #endif 
    
    /* Execute user permission */  
    #if !defined(S_IXUSR) 
    # define S_IXUSR 0 
    #endif 
    
    /* Read group permission */  
    #if !defined(S_IRGRP) 
    # define S_IRGRP 0 
    #endif 
    
    /* Write group permission */  
    #if !defined(S_IWGRP) 
    # define S_IWGRP 0 
    #endif 
    
    /* Execute group permission */  
    #if !defined(S_IXGRP) 
    # define S_IXGRP 0 
    #endif 
    
    /* Read others permission */  
    #if !defined(S_IROTH) 
    # define S_IROTH 0 
    #endif 
    
    /* Write others permission */  
    #if !defined(S_IWOTH) 
    # define S_IWOTH 0 
    #endif 
    
    /* Execute others permission */  
    #if !defined(S_IXOTH) 
    # define S_IXOTH 0 
    #endif 
    
    /* Maximum length of file name */  
    #if !defined(PATH_MAX) 
    # define PATH_MAX MAX_PATH 
    #endif 
    #if !defined(FILENAME_MAX) 
    # define FILENAME_MAX MAX_PATH 
    #endif 
    #if !defined(NAME_MAX) 
    # define NAME_MAX FILENAME_MAX 
    #endif 
    
    /* File type flags for d_type */  
    #define DT_UNKNOWN 0 
    #define DT_REG S_IFREG 
    #define DT_DIR S_IFDIR 
    #define DT_FIFO S_IFIFO 
    #define DT_SOCK S_IFSOCK 
    #define DT_CHR S_IFCHR 
    #define DT_BLK S_IFBLK 
    #define DT_LNK S_IFLNK 
    
    /* Macros for converting between st_mode and d_type */  
    #define IFTODT(mode) ((mode) & S_IFMT) 
    #define DTTOIF(type) (type) 
    
    /* * File type macros. Note that block devices, sockets and links cannot be * distinguished on Windows and the macros S_ISBLK, S_ISSOCK and S_ISLNK are * only defined for compatibility. These macros should always return false * on Windows. */  
    #if !defined(S_ISFIFO) 
    # define S_ISFIFO(mode) (((mode) & S_IFMT) == S_IFIFO) 
    #endif 
    #if !defined(S_ISDIR) 
    # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR) 
    #endif 
    #if !defined(S_ISREG) 
    # define S_ISREG(mode) (((mode) & S_IFMT) == S_IFREG) 
    #endif 
    #if !defined(S_ISLNK) 
    # define S_ISLNK(mode) (((mode) & S_IFMT) == S_IFLNK) 
    #endif 
    #if !defined(S_ISSOCK) 
    # define S_ISSOCK(mode) (((mode) & S_IFMT) == S_IFSOCK) 
    #endif 
    #if !defined(S_ISCHR) 
    # define S_ISCHR(mode) (((mode) & S_IFMT) == S_IFCHR) 
    #endif 
    #if !defined(S_ISBLK) 
    # define S_ISBLK(mode) (((mode) & S_IFMT) == S_IFBLK) 
    #endif 
    
    /* Return the exact length of d_namlen without zero terminator */  
    #define _D_EXACT_NAMLEN(p) ((p)->d_namlen) 
    
    /* Return number of bytes needed to store d_namlen */  
    #define _D_ALLOC_NAMLEN(p) (PATH_MAX) 
    
    
    #ifdef __cplusplus 
    extern "C" {  
    #endif 
    
    
    /* Wide-character version */  
    struct _wdirent {  
        /* Always zero */  
        long d_ino;  
    
        /* Structure size */  
        unsigned short d_reclen;  
    
        /* Length of name without \0 */  
        size_t d_namlen;  
    
        /* File type */  
        int d_type;  
    
        /* File name */  
        wchar_t d_name[PATH_MAX];  
    };  
    typedef struct _wdirent _wdirent;  
    
    struct _WDIR {  
        /* Current directory entry */  
        struct _wdirent ent;  
    
        /* Private file data */  
        WIN32_FIND_DATAW data;  
    
        /* True if data is valid */  
        int cached;  
    
        /* Win32 search handle */  
        HANDLE handle;  
    
        /* Initial directory name */  
        wchar_t *patt;  
    };  
    typedef struct _WDIR _WDIR;  
    
    static _WDIR *_wopendir (const wchar_t *dirname);  
    static struct _wdirent *_wreaddir (_WDIR *dirp);  
    static int _wclosedir (_WDIR *dirp);  
    static void _wrewinddir (_WDIR* dirp);  
    
    
    /* For compatibility with Symbian */  
    #define wdirent _wdirent 
    #define WDIR _WDIR 
    #define wopendir _wopendir 
    #define wreaddir _wreaddir 
    #define wclosedir _wclosedir 
    #define wrewinddir _wrewinddir 
    
    
    /* Multi-byte character versions */  
    struct dirent {  
        /* Always zero */  
        long d_ino;  
    
        /* Structure size */  
        unsigned short d_reclen;  
    
        /* Length of name without \0 */  
        size_t d_namlen;  
    
        /* File type */  
        int d_type;  
    
        /* File name */  
        char d_name[PATH_MAX];  
    };  
    typedef struct dirent dirent;  
    
    struct DIR {  
        struct dirent ent;  
        struct _WDIR *wdirp;  
    };  
    typedef struct DIR DIR;  
    
    static DIR *opendir (const char *dirname);  
    static struct dirent *readdir (DIR *dirp);  
    static int closedir (DIR *dirp);  
    static void rewinddir (DIR* dirp);  
    
    
    /* Internal utility functions */  
    static WIN32_FIND_DATAW *dirent_first (_WDIR *dirp);  
    static WIN32_FIND_DATAW *dirent_next (_WDIR *dirp);  
    
    static int dirent_mbstowcs_s(  
        size_t *pReturnValue,  
        wchar_t *wcstr,  
        size_t sizeInWords,  
        const char *mbstr,  
        size_t count);  
    
    static int dirent_wcstombs_s(  
        size_t *pReturnValue,  
        char *mbstr,  
        size_t sizeInBytes,  
        const wchar_t *wcstr,  
        size_t count);  
    
    static void dirent_set_errno (int error);  
    
    /* * Open directory stream DIRNAME for read and return a pointer to the * internal working area that is used to retrieve individual directory * entries. */  
    static _WDIR*  
    _wopendir(  
        const wchar_t *dirname)  
    {  
        _WDIR *dirp = NULL;  
        int error;  
    
        /* Must have directory name */  
        if (dirname == NULL  ||  dirname[0] == '\0') {  
            dirent_set_errno (ENOENT);  
            return NULL;  
        }  
    
        /* Allocate new _WDIR structure */  
        dirp = (_WDIR*) malloc (sizeof (struct _WDIR));  
        if (dirp != NULL) {  
            DWORD n;  
    
            /* Reset _WDIR structure */  
            dirp->handle = INVALID_HANDLE_VALUE;  
            dirp->patt = NULL;  
            dirp->cached = 0;  
    
            /* Compute the length of full path plus zero terminator */  
            n = GetFullPathNameW (dirname, 0, NULL, NULL);  
    
            /* Allocate room for absolute directory name and search pattern */  
            dirp->patt = (wchar_t*) malloc (sizeof (wchar_t) * n + 16);  
            if (dirp->patt) {  
    
                /* * Convert relative directory name to an absolute one. This * allows rewinddir() to function correctly even when current * working directory is changed between opendir() and rewinddir(). */  
                n = GetFullPathNameW (dirname, n, dirp->patt, NULL);  
                if (n > 0) {  
                    wchar_t *p;  
    
                    /* Append search pattern \* to the directory name */  
                    p = dirp->patt + n;  
                    if (dirp->patt < p) {  
                        switch (p[-1]) {  
                        case '\\':  
                        case '/':  
                        case ':':  
                            /* Directory ends in path separator, e.g. c:\temp\ */  
                            /*NOP*/;  
                            break;  
    
                        default:  
                            /* Directory name doesn't end in path separator */  
                            *p++ = '\\';  
                        }  
                    }  
                    *p++ = '*';  
                    *p = '\0';  
    
                    /* Open directory stream and retrieve the first entry */  
                    if (dirent_first (dirp)) {  
                        /* Directory stream opened successfully */  
                        error = 0;  
                    } else {  
                        /* Cannot retrieve first entry */  
                        error = 1;  
                        dirent_set_errno (ENOENT);  
                    }  
    
                } else {  
                    /* Cannot retrieve full path name */  
                    dirent_set_errno (ENOENT);  
                    error = 1;  
                }  
    
            } else {  
                /* Cannot allocate memory for search pattern */  
                error = 1;  
            }  
    
        } else {  
            /* Cannot allocate _WDIR structure */  
            error = 1;  
        }  
    
        /* Clean up in case of error */  
        if (error  &&  dirp) {  
            _wclosedir (dirp);  
            dirp = NULL;  
        }  
    
        return dirp;  
    }  
    
    /* * Read next directory entry. The directory entry is returned in dirent * structure in the d_name field. Individual directory entries returned by * this function include regular files, sub-directories, pseudo-directories * "." and ".." as well as volume labels, hidden files and system files. */  
    static struct _wdirent*  
    _wreaddir(  
        _WDIR *dirp)  
    {  
        WIN32_FIND_DATAW *datap;  
        struct _wdirent *entp;  
    
        /* Read next directory entry */  
        datap = dirent_next (dirp);  
        if (datap) {  
            size_t n;  
            DWORD attr;  
    
            /* Pointer to directory entry to return */  
            entp = &dirp->ent;  
    
            /* * Copy file name as wide-character string. If the file name is too * long to fit in to the destination buffer, then truncate file name * to PATH_MAX characters and zero-terminate the buffer. */  
            n = 0;  
            while (n + 1 < PATH_MAX  &&  datap->cFileName[n] != 0) {  
                entp->d_name[n] = datap->cFileName[n];  
                n++;  
            }  
            dirp->ent.d_name[n] = 0;  
    
            /* Length of file name excluding zero terminator */  
            entp->d_namlen = n;  
    
            /* File type */  
            attr = datap->dwFileAttributes;  
            if ((attr & FILE_ATTRIBUTE_DEVICE) != 0) {  
                entp->d_type = DT_CHR;  
            } else if ((attr & FILE_ATTRIBUTE_DIRECTORY) != 0) {  
                entp->d_type = DT_DIR;  
            } else {  
                entp->d_type = DT_REG;  
            }  
    
            /* Reset dummy fields */  
            entp->d_ino = 0;  
            entp->d_reclen = sizeof (struct _wdirent);  
    
        } else {  
    
            /* Last directory entry read */  
            entp = NULL;  
    
        }  
    
        return entp;  
    }  
    
    /* * Close directory stream opened by opendir() function. This invalidates the * DIR structure as well as any directory entry read previously by * _wreaddir(). */  
    static int  
    _wclosedir(  
        _WDIR *dirp)  
    {  
        int ok;  
        if (dirp) {  
    
            /* Release search handle */  
            if (dirp->handle != INVALID_HANDLE_VALUE) {  
                FindClose (dirp->handle);  
                dirp->handle = INVALID_HANDLE_VALUE;  
            }  
    
            /* Release search pattern */  
            if (dirp->patt) {  
                free (dirp->patt);  
                dirp->patt = NULL;  
            }  
    
            /* Release directory structure */  
            free (dirp);  
            ok = /*success*/0;  
    
        } else {  
            /* Invalid directory stream */  
            dirent_set_errno (EBADF);  
            ok = /*failure*/-1;  
        }  
        return ok;  
    }  
    
    /* * Rewind directory stream such that _wreaddir() returns the very first * file name again. */  
    static void  
    _wrewinddir(  
        _WDIR* dirp)  
    {  
        if (dirp) {  
            /* Release existing search handle */  
            if (dirp->handle != INVALID_HANDLE_VALUE) {  
                FindClose (dirp->handle);  
            }  
    
            /* Open new search handle */  
            dirent_first (dirp);  
        }  
    }  
    
    /* Get first directory entry (internal) */  
    static WIN32_FIND_DATAW*  
    dirent_first(  
        _WDIR *dirp)  
    {  
        WIN32_FIND_DATAW *datap;  
    
        /* Open directory and retrieve the first entry */  
        dirp->handle = FindFirstFileW (dirp->patt, &dirp->data);  
        if (dirp->handle != INVALID_HANDLE_VALUE) {  
    
            /* a directory entry is now waiting in memory */  
            datap = &dirp->data;  
            dirp->cached = 1;  
    
        } else {  
    
            /* Failed to re-open directory: no directory entry in memory */  
            dirp->cached = 0;  
            datap = NULL;  
    
        }  
        return datap;  
    }  
    
    /* Get next directory entry (internal) */  
    static WIN32_FIND_DATAW*  
    dirent_next(  
        _WDIR *dirp)  
    {  
        WIN32_FIND_DATAW *p;  
    
        /* Get next directory entry */  
        if (dirp->cached != 0) {  
    
            /* A valid directory entry already in memory */  
            p = &dirp->data;  
            dirp->cached = 0;  
    
        } else if (dirp->handle != INVALID_HANDLE_VALUE) {  
    
            /* Get the next directory entry from stream */  
            if (FindNextFileW (dirp->handle, &dirp->data) != FALSE) {  
                /* Got a file */  
                p = &dirp->data;  
            } else {  
                /* The very last entry has been processed or an error occured */  
                FindClose (dirp->handle);  
                dirp->handle = INVALID_HANDLE_VALUE;  
                p = NULL;  
            }  
    
        } else {  
    
            /* End of directory stream reached */  
            p = NULL;  
    
        }  
    
        return p;  
    }  
    
    /* * Open directory stream using plain old C-string. */  
    static DIR*  
    opendir(  
        const char *dirname)   
    {  
        struct DIR *dirp;  
        int error;  
    
        /* Must have directory name */  
        if (dirname == NULL  ||  dirname[0] == '\0') {  
            dirent_set_errno (ENOENT);  
            return NULL;  
        }  
    
        /* Allocate memory for DIR structure */  
        dirp = (DIR*) malloc (sizeof (struct DIR));  
        if (dirp) {  
            wchar_t wname[PATH_MAX];  
            size_t n;  
    
            /* Convert directory name to wide-character string */  
            error = dirent_mbstowcs_s (&n, wname, PATH_MAX, dirname, PATH_MAX);  
            if (!error) {  
    
                /* Open directory stream using wide-character name */  
                dirp->wdirp = _wopendir (wname);  
                if (dirp->wdirp) {  
                    /* Directory stream opened */  
                    error = 0;  
                } else {  
                    /* Failed to open directory stream */  
                    error = 1;  
                }  
    
            } else {  
                /* * Cannot convert file name to wide-character string. This * occurs if the string contains invalid multi-byte sequences or * the output buffer is too small to contain the resulting * string. */  
                error = 1;  
            }  
    
        } else {  
            /* Cannot allocate DIR structure */  
            error = 1;  
        }  
    
        /* Clean up in case of error */  
        if (error  &&  dirp) {  
            free (dirp);  
            dirp = NULL;  
        }  
    
        return dirp;  
    }  
    
    /* * Read next directory entry. * * When working with text consoles, please note that file names returned by * readdir() are represented in the default ANSI code page while any output to * console is typically formatted on another code page. Thus, non-ASCII * characters in file names will not usually display correctly on console. The * problem can be fixed in two ways: (1) change the character set of console * to 1252 using chcp utility and use Lucida Console font, or (2) use * _cprintf function when writing to console. The _cprinf() will re-encode * ANSI strings to the console code page so many non-ASCII characters will * display correcly. */  
    static struct dirent*  
    readdir(  
        DIR *dirp)   
    {  
        WIN32_FIND_DATAW *datap;  
        struct dirent *entp;  
    
        /* Read next directory entry */  
        datap = dirent_next (dirp->wdirp);  
        if (datap) {  
            size_t n;  
            int error;  
    
            /* Attempt to convert file name to multi-byte string */  
            error = dirent_wcstombs_s(  
                &n, dirp->ent.d_name, PATH_MAX, datap->cFileName, PATH_MAX);  
    
            /* * If the file name cannot be represented by a multi-byte string, * then attempt to use old 8+3 file name. This allows traditional * Unix-code to access some file names despite of unicode * characters, although file names may seem unfamiliar to the user. * * Be ware that the code below cannot come up with a short file * name unless the file system provides one. At least * VirtualBox shared folders fail to do this. */  
            if (error  &&  datap->cAlternateFileName[0] != '\0') {  
                error = dirent_wcstombs_s(  
                    &n, dirp->ent.d_name, PATH_MAX,   
                    datap->cAlternateFileName, PATH_MAX);  
            }  
    
            if (!error) {  
                DWORD attr;  
    
                /* Initialize directory entry for return */  
                entp = &dirp->ent;  
    
                /* Length of file name excluding zero terminator */  
                entp->d_namlen = n - 1;  
    
                /* File attributes */  
                attr = datap->dwFileAttributes;  
                if ((attr & FILE_ATTRIBUTE_DEVICE) != 0) {  
                    entp->d_type = DT_CHR;  
                } else if ((attr & FILE_ATTRIBUTE_DIRECTORY) != 0) {  
                    entp->d_type = DT_DIR;  
                } else {  
                    entp->d_type = DT_REG;  
                }  
    
                /* Reset dummy fields */  
                entp->d_ino = 0;  
                entp->d_reclen = sizeof (struct dirent);  
    
            } else {  
                /* * Cannot convert file name to multi-byte string so construct * an errornous directory entry and return that. Note that * we cannot return NULL as that would stop the processing * of directory entries completely. */  
                entp = &dirp->ent;  
                entp->d_name[0] = '?';  
                entp->d_name[1] = '\0';  
                entp->d_namlen = 1;  
                entp->d_type = DT_UNKNOWN;  
                entp->d_ino = 0;  
                entp->d_reclen = 0;  
            }  
    
        } else {  
            /* No more directory entries */  
            entp = NULL;  
        }  
    
        return entp;  
    }  
    
    /* * Close directory stream. */  
    static int  
    closedir(  
        DIR *dirp)   
    {  
        int ok;  
        if (dirp) {  
    
            /* Close wide-character directory stream */  
            ok = _wclosedir (dirp->wdirp);  
            dirp->wdirp = NULL;  
    
            /* Release multi-byte character version */  
            free (dirp);  
    
        } else {  
    
            /* Invalid directory stream */  
            dirent_set_errno (EBADF);  
            ok = /*failure*/-1;  
    
        }  
        return ok;  
    }  
    
    /* * Rewind directory stream to beginning. */  
    static void  
    rewinddir(  
        DIR* dirp)   
    {  
        /* Rewind wide-character string directory stream */  
        _wrewinddir (dirp->wdirp);  
    }  
    
    /* Convert multi-byte string to wide character string */  
    static int  
    dirent_mbstowcs_s(  
        size_t *pReturnValue,  
        wchar_t *wcstr,  
        size_t sizeInWords,  
        const char *mbstr,  
        size_t count)  
    {  
        int error;  
    
    #if defined(_MSC_VER) && _MSC_VER >= 1400 
    
        /* Microsoft Visual Studio 2005 or later */  
        error = mbstowcs_s (pReturnValue, wcstr, sizeInWords, mbstr, count);  
    
    #else 
    
        /* Older Visual Studio or non-Microsoft compiler */  
        size_t n;  
    
        /* Convert to wide-character string (or count characters) */  
        n = mbstowcs (wcstr, mbstr, sizeInWords);  
        if (!wcstr  ||  n < count) {  
    
            /* Zero-terminate output buffer */  
            if (wcstr  &&  sizeInWords) {  
                if (n >= sizeInWords) {  
                    n = sizeInWords - 1;  
                }  
                wcstr[n] = 0;  
            }  
    
            /* Length of resuting multi-byte string WITH zero terminator */  
            if (pReturnValue) {  
                *pReturnValue = n + 1;  
            }  
    
            /* Success */  
            error = 0;  
    
        } else {  
    
            /* Could not convert string */  
            error = 1;  
    
        }  
    
    #endif 
    
        return error;  
    }  
    
    /* Convert wide-character string to multi-byte string */  
    static int  
    dirent_wcstombs_s(  
        size_t *pReturnValue,  
        char *mbstr,  
        size_t sizeInBytes, /* max size of mbstr */  
        const wchar_t *wcstr,  
        size_t count)  
    {  
        int error;  
    
    #if defined(_MSC_VER) && _MSC_VER >= 1400 
    
        /* Microsoft Visual Studio 2005 or later */  
        error = wcstombs_s (pReturnValue, mbstr, sizeInBytes, wcstr, count);  
    
    #else 
    
        /* Older Visual Studio or non-Microsoft compiler */  
        size_t n;  
    
        /* Convert to multi-byte string (or count the number of bytes needed) */  
        n = wcstombs (mbstr, wcstr, sizeInBytes);  
        if (!mbstr  ||  n < count) {  
    
            /* Zero-terminate output buffer */  
            if (mbstr  &&  sizeInBytes) {  
                if (n >= sizeInBytes) {  
                    n = sizeInBytes - 1;  
                }  
                mbstr[n] = '\0';  
            }  
    
            /* Lenght of resulting multi-bytes string WITH zero-terminator */  
            if (pReturnValue) {  
                *pReturnValue = n + 1;  
            }  
    
            /* Success */  
            error = 0;  
    
        } else {  
    
            /* Cannot convert string */  
            error = 1;  
    
        }  
    
    #endif 
    
        return error;  
    }  
    
    /* Set errno variable */  
    static void  
    dirent_set_errno(  
        int error)  
    {  
    #if defined(_MSC_VER) && _MSC_VER >= 1400 
    
        /* Microsoft Visual Studio 2005 and later */  
        _set_errno (error);  
    
    #else 
    
        /* Non-Microsoft compiler or older Microsoft compiler */  
        errno = error;  
    
    #endif 
    }  
    
    
    #ifdef __cplusplus 
    }  
    #endif 
    #endif /*DIRENT_H*/

**方法四：调用opencv中的Directory库：**

比起前几种方法，个人感觉这种方法最靠谱，代码简洁，方便的调用：

#include<opencv2/opencv.hpp> 
    #include<iostream> 
    #include<vector> 
    #include<string> 
    #include <windows.h> 
    
    using namespace std;
    using namespace cv;
    
    
    int main()
    {
        Directory dir;
    
        string path1 = "E:\\vsproject\\opencv\\opencvTest\\opencvTest\\印刷体\\印刷体大写金额";
        string  exten1 = "*.png";
    
        vector<string> filenames = dir.GetListFiles(path1, exten1, false);
    
        int size = filenames.size();
    
        for (int i = 0; i < size; i++)
        {
            cout << filenames[i] << endl;
        }
        system("pause");
        return 0;
    }

————————————————————————————总结完毕