C++ 实用的小程序

１．　打开test_ids.txt　将里面的东西添加"1_",然后另存为test_ids_repaired.txt

 #include <iostream>
 #include <string>
 #include <fstream>
 #include <sstream>
 #include <iostream>
 using namespace std;
 int main(){

     ifstream file;
     file.open("/home/wangxiao/Downloads/Link to ASPL---code/features/test_ids.txt");
     ofstream in("/home/wangxiao/Downloads/test_ids_repaired.txt");

     std::string line;
     std::string image_id;

     while(getline(file, line)){
         std::string add = "1_";
         line = add + line;

         image_id = line;
         in<<image_id<<endl;
     }
  }

2 : 编写一个程序，读入string和int的序列，将每个string和int存入一个pair中，pair保存在一个vector中．

 ＃include<iostream>
 #include<fstream>
 #include<utility>
 #include<vector>
 #include<string>
 #include<algorithm>

 using namespace std;
 int main(int argc, char *argv[])
 {
       ifstream in(argv[]);
       if (!in) {
           cout<<”打开输入文件失败！”<<endl;
           exit();
       }

 vector<pair<string, int>> data;
 string s;
 int v;
 while (in>>s && in>>v)
      data.push_back(pair<string, int>(s, v));
   // data.push_back({s, v});  列表初始化的方式；
   // data.push_back(make_pair(s, v));　或者使用 make_pair ;

 for (const auto &d : data)
      cout<<d.first<<” ---> ”<<d.second<<endl;

    return ;
 }

3. 打开test_ids.txt　将里面的东西添加"i_",然后另存为test_ids_repaired.txt  从１～88种　．．．

 #include <iostream>
 #include <string>
 #include <fstream>
 #include <sstream>
 #include <iostream>
 using namespace std;

 int main(){

     ifstream file;
     file.open("/home/wangxiao/Downloads/ASPL_matlabFiles/test_ids.txt");
     ofstream in("/home/wangxiao/Downloads/ASPL_matlabFiles/outPut_test_ids.txt");

     std::string line;
     std::string image_id;

 for (int i=;i<;i++){

    for (int j=;j<;j++){

        getline(file, line);
        stringstream ss;
        string s;
        ss << i;
        ss >> s;
        string add = s + "_";
        image_id = add + line;
        in<<image_id<<endl;

    }
 }
  }