C++ Code(持續更新)－Yang的部落格(轉貼文章請註記來源)

以下C++程式已在Windows Visual Studio 2017試驗過

字串轉整數(string to int)

#include <stdlib.h>
#include <string>

using namespace std;

int str2int(string str)
{
return atoi(str.c_str());
}

整數轉字串(int to string)

#include <sstream>
#include <string>

using namespace std;

string int2str(int num)
{
   string s;
   stringstream ss(s);
   ss << num;

return ss.str();
}

字串轉字元陣列(string to char array)

#include <string>

using namespace std;

char* str2chArray(string str)
{
   char* tmp;
   int size = str.length();
   tmp = new char[sizeof(char) * (size + 1)];
   for (int i = 0; i < str.length(); i++) tmp[i] = str[i];
   tmp[size] = '\0';

return tmp;
}

字元陣列轉字串(char array to string)

#include <string>

using namespace std;

string chArray2str(char* ch)
{
string str(ch);
return str;
}

字串切割(Split)

#include <vector>
#include <string>

using namespace std;

vector<string> Split(string str, string delimiter)
{
vector<string> data = vector<string>();

   char* pch;
   pch = strtok(str2chArray(str), str2chArray(delimiter));
   while (pch != NULL)
   {
       data.push_back(chArray2str(pch));
       pch = strtok(NULL, str2chArray(delimiter));
   }
   return data;
}

判斷檔案是否存在(is file exist)

#include <fstream>

using namespace std;

bool isFileExist(string filename)
{
   FILE* fin = fopen(str2chArray(filename), "r");
   if (!fin) return false;
   else return true;
}

取得資料夾下的所有檔案(包含子資料夾內的檔案)

需使用dirent.h

#include "dirent.h"
#include <vector>
#include <string>

#include <stdlib.h>

#define Platform_Windows
//#define Platform_Linux

using namespace std;

void GetFiles(char* path, vector<string>& files)
{
#ifdef Platform_Windows
   char glue = '\\';//Windows的分隔符號
#elif Platform_Linux
   //char glue='/';//Linux 的分隔符號
#else
   cout << "***[ERROR]Platform error\n"
#endif

   DIR* dp = opendir(path);
   if (!dp)
   {
       // 不是目錄
       files.push_back(chArray2str(path));
       return;
   }

   struct dirent* filename;
   while ((filename = readdir(dp)))
   {
       //跳過當前及母目錄
       if (!strcmp(filename->d_name, "..") || !strcmp(filename->d_name, ".")) continue;

       //計算新的路徑字串所需的長度
       int pathLength = strlen(path) + strlen(filename->d_name) + 2;

       //產生新的陣列空間
       char* pathStr = new char[sizeof(char) * pathLength];

       //複製當前目錄路徑至新的陣列空間
       strcpy(pathStr, path);

       //檢查目錄分隔符號
       int i = strlen(pathStr);
       if (pathStr[i - 1] != glue)
       {
           pathStr[i] = glue;
           pathStr[i + 1] = '\0';
       }

       //串接次目錄名稱或檔案名稱至新的陣列空間
       strcat(pathStr, filename->d_name);

       //遞迴呼叫目錄掃瞄
       GetFiles(pathStr, files);
   }
}

從txt檔一次讀取一行資料(getline)

#include <string>
#include <fstream>
#include <vector>

using namespace std;

vector<string> GetData(char* path)
{
   vector<string> dataVec;
   string data;
   fstream file;
   file.open(path);
   while (getline(file, data))
   {
       dataVec.push_back(data);
   }
   return dataVec;
}

找出vector中的最大值和最小值

#include <vector>
using namespace std;

int main()
{
   vector<int> data = {1, 2, 5, -1, 0, 4};
   int max = *std::max_element(std::begin(data), std::end(data));
   int min = *std::min_element(std::begin(data), std::end(data));
}