一大波实用Function，再也不用去盘里一个一个找了

1.Linux时间戳

#include <time.h>
#include <sys/time.h>

std::string get_time()
{
    time_t tt = time(NULL);//这句返回的只是一个时间cuo
    tm* t= localtime(&tt);
    char ti[128];
    sprintf(ti,"%d-%02d-%02d_%02d-%02d-%02d",t->tm_year + 1900, t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
    std::string ttt = ti;
    printf("time: %s\n",ti);
    return ttt;
}

2.字符串分割（非常实用）头文件不列，win,linux均测试

void SplitString(const string& s, vector<string>& v, const string& c)
{
    string::size_type pos1, pos2;
    pos2 = s.find(c);
    pos1 = 0;
    while (string::npos != pos2)
    {
        v.push_back(s.substr(pos1, pos2 - pos1));

        pos1 = pos2 + c.size();
        pos2 = s.find(c, pos1);
    }
    if (pos1 != s.length())
        v.push_back(s.substr(pos1));
}

3.string2*,win linux均测试

int str2int(const string str)
{
    int temp;
    stringstream stream(str);
    stream>>temp;
    return temp;
}

如果要2其他（float double等），直接将int换成其他

4.opencv Rect按中心点外扩Size,头文件不贴

Rect rectCenterScale(Rect rect, Size size)
{
    rect = rect + size;
    Point pt;
    pt.x = cvRound(size.width/2.0);
    pt.y = cvRound(size.height/2.0);
    return (rect-pt);
}

5.创建文件夹

#include <stdio.h>
#include <mutex>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/stat.h>

int creat_dir(std::string dir)
{
    if (access(dir.c_str(), 0) == -1)
    {
        std::cout << dir << " is not existing" << std::endl;
        cout << "now make it" << endl;
#ifdef WIN32  
        int flag=mkdir(dir.c_str());
#endif
#ifdef LINUX   
        int flag=mkdir(dir.c_str(), 0777);
#endif
        if (flag == 0)
        {
            std::cout << "make successfully" << std::endl;
        } else {
            std::cout << "make errorly" << std::endl;
        }
    }
    return 0;
}

这个头文件还真忘了，应该就是其中几个(Linux)。win加预处理器定义或者修改mkdir为_mkdir，头文件为#include <direct.h>。

6.base642Mat（base64码转opencv Mat）

static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";

std::string base64_decode(std::string const &encoded_string) {
	int in_len = encoded_string.size();
	int i = 0;
	int j = 0;
	int in_ = 0;
	unsigned char char_array_4[4], char_array_3[3];
	std::string ret;

	while (in_len-- && (encoded_string[in_] != '=')) {
		char_array_4[i++] = encoded_string[in_]; in_++;
		if (i == 4) {
			for (i = 0; i < 4; i++)
				char_array_4[i] = base64_chars.find(char_array_4[i]);

			char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
			char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
			char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

			for (i = 0; (i < 3); i++)
				ret += char_array_3[i];
			i = 0;
		}
	}

	if (i) {
		for (j = i; j < 4; j++)
			char_array_4[j] = 0;

		for (j = 0; j < 4; j++)
			char_array_4[j] = base64_chars.find(char_array_4[j]);

		char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
		char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
		char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

		for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
	}

	return ret;
}

cv::Mat base64ToMat(string &base64) {
	string decoded_string = base64_decode(base64);
	std::vector<uchar> data(decoded_string.begin(), decoded_string.end());
	cv::Mat image = cv::imdecode(data, CV_LOAD_IMAGE_UNCHANGED);
	return image;
}

头文件就不贴了。win linux亲测

7.Mat2Base64（opencv Mat 转base64码）

static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";

std::string base64_encode(const char* bytes_to_encode, int in_len) {
	std::string ret;
	int i = 0;
	int j = 0;
	unsigned char char_array_3[3];
	unsigned char char_array_4[4];

	while (in_len--) {
		char_array_3[i++] = *(bytes_to_encode++);
		if (i == 3) {
			char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
			char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
			char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
			char_array_4[3] = char_array_3[2] & 0x3f;

			for (i = 0; (i <4); i++)
				ret += base64_chars[char_array_4[i]];
			i = 0;
		}
	}

	if (i)
	{
		for (j = i; j < 3; j++)
			char_array_3[j] = '\0';

		char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
		char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
		char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
		char_array_4[3] = char_array_3[2] & 0x3f;

		for (j = 0; (j < i + 1); j++)
			ret += base64_chars[char_array_4[j]];

		while ((i++ < 3))
			ret += '=';

	}
	return ret;
}

std::string matToBase64(cv::Mat img)
{
	std::vector<uchar> data_encode;
	cv::imencode(".jpg", img, data_encode);
	std::string str_encode(data_encode.begin(), data_encode.end());
	string base64String = base64_encode(str_encode.c_str(), str_encode.length());
	return base64String;
}

8.json读和取，需要jsoncpp.cpp和json.h。网上一搜一大把

扫描二维码关注公众号，回复： 1732591 查看本文章

写

std::string getJsonString(parameter *P) {
	Json::FastWriter writer;
	Json::Value root;
	root["flage"] = P->flage;
	//root["ID_base64"] = P->ID_base64;
	//root["img_base64"] = P->img_base64;
	root["up_img_base64"] = P->up_img;
	root["db"] = P->db;
	
	//root["Compare_image"] = P->Compare_image;
	//root["Feature"] = P->Feature;
	//root["Score"] = P->Score;
	std::string jsonString = writer.write(root);
	return jsonString;
}

读

Json::Reader reader;
Json::Value root;
string ID_base64;
string base_image_base64;
if (reader.parse(postResponseStr, root)) {
	ID_base64 =  root["ID_Base64"].asString();
	base_image_base64 = root["Compare_image"].asString();
}

----------------------------------
未完待续
----------------------------------