C++实用记录

一、工作中有时会用到的一些功能，记录下来

//遍历文件夹下的文件，输入：文件夹路径，返回文件名的vector
void get_image_names(const string &file_path, vector<string>&file_names)
{
    intptr_t hFile = 0;
    //文件信息的结构体
    _finddata_t fileInfo;
    //第一次查找
    hFile = _findfirst(file_path.c_str(), &fileInfo);
    if (hFile != -1) {
        do {
            if ((fileInfo.attrib &  _A_SUBDIR)) {
                continue;
            }
            else {
                file_names.push_back(fileInfo.name);
                //cout << fileInfo.name << endl;
            }
        } while (_findnext(hFile, &fileInfo) == 0);

        _findclose(hFile);
    }
}

//调用方式


vector<string> filenames;
string filepath = "";
get_image_names(filepath + "*.jpg", filenames);

void getFiles(string path, vector<string>& files)
/*获取目录下的文件*/
{
//文件句柄
intptr_t hFile = 0;
//文件信息
struct _finddata_t fileinfo;
string p;
if ((hFile = _findfirst(p.assign(path).append("\*").c_str(), &fileinfo)) != -1)
{
do
{
//如果是目录,迭代之，如果不是目录那一步删除
if ((fileinfo.attrib & _A_SUBDIR))
{
if (strcmp(fileinfo.name, ".") != 0 && strcmp(fileinfo.name, "..") != 0)
getFiles(p.assign(path).append("\").append(fileinfo.name), files);
}
else
{
files.push_back(p.assign(path).append("\").append(fileinfo.name));
}
} while (_findnext(hFile, &fileinfo) == 0);
_findclose(hFile);
}
}

//另一种比较方便的方法是，利用opencv中的glob
string filepath = "";
vector<String> filenames;
glob(filepath, filenames,true);
for (auto c : filenames) {
std::cout << "正在处理：" << c << "..." << std::endl;
        int pos = c.find_last_of('\');
        string s(c.substr(pos + 1));
}          
//不过数据类型为cv::String
所以要不是opencv直接用一般需要转类型，比如char*或者string类型
USES_CONVERSION;
cv::String b = filename;
string c = b;
const char *p = c.data();

  

//根据指定pattern对字符串进行切分，类似python中的split
vector<string> split(const string &str, const string &pattern)
{
    /*基于find和substr函数实现字符串切割*/
    vector<string> res;
    if (str == "")
        return res;
    //在字符串末尾也加入分隔符，方便截取最后一段
    string strs = str + pattern;
    //pos为strs中pattern出现的第一个位置
    size_t pos = strs.find(pattern);
    //npos在 c++中表示一个常数，表示不存在的位置,npos 是这样定义的static const size_type npos = -1;
    //所以pos 也为size_t类型，不能定义为int
    while (pos != strs.npos)
    {
        string temp = strs.substr(0, pos);
        res.push_back(temp);
        //去掉已分割的字符串,在剩下的字符串中进行分割
        strs = strs.substr(pos + 1, strs.size());
        pos = strs.find(pattern);
    }
    return res;
}

//调用举例

vector<string> res;
res = split(txtfile, "\");

//解决读取中文编码乱码的情况
string UTF8ToGB(const char* str)
{
    string result;
    WCHAR *strSrc;
    LPSTR szRes;

    //获得临时变量的大小
    int i = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
    strSrc = new WCHAR[i + 1];
    MultiByteToWideChar(CP_UTF8, 0, str, -1, strSrc, i);

    //获得临时变量的大小
    i = WideCharToMultiByte(CP_ACP, 0, strSrc, -1, NULL, 0, NULL, NULL);
    szRes = new CHAR[i + 1];
    WideCharToMultiByte(CP_ACP, 0, strSrc, -1, szRes, i, NULL, NULL);

    result = szRes;
    delete[]strSrc;
    delete[]szRes;

    return result;
}

//将文件复制到指定文件夹
void copy_file(int flag,string s,string name) {
    string source = "";
    string target = "";
    string target1 = "";
    string source_path = source + s+ "\"+name;
    LPCSTR source_path1 = source_path.c_str();
    if (flag == 1){
        string target_path = target + s + "\";
        //cout << target_path << endl;
        if (0 != _access(target_path.c_str(), 0))
        {
            _mkdir(target_path.c_str());   // 返回 0 表示创建成功，-1 表示失败
        }
        string target_path_name = target_path + name;
        LPCSTR target_path_name1 = target_path_name.c_str();
        //cout << target_path_name1 << endl;
        CopyFile(source_path1, target_path_name1, TRUE);//false代表覆盖，true不覆盖
    }
    else {
        string target_path1 = target1 + s + "\";
        //cout << target_path << endl;
        if (0 != _access(target_path1.c_str(), 0))
        {
            _mkdir(target_path1.c_str());   // 返回 0 表示创建成功，-1 表示失败
        }
        string target_path_name1 = target_path1 + name;
        LPCSTR target_path_name2 = target_path_name1.c_str();
        //cout << target_path_name1 << endl;
        CopyFile(source_path1, target_path_name2, TRUE);//false代表覆盖，true不覆盖
    }

}