C++ codes

#include <iostream>
using namespace std;

int main()
{
    
    
  string text="data.txt";
  cout<<text.replace((text.size()-3),3,"jpg")<<endl;
  cout<<("love "+text)<<endl;
}

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

vector<string> vec;
string a[18];
int i=0;
ifstream in_file("data.txt");

string str_line;

int main()
{
    
    

  while(getline(in_file,str_line,','))
  {
    
    
    string str_tmp;
    stringstream ss(str_line);
    while(ss>>str_tmp)
    {
    
       
    
      a[i]=str_tmp;
      cout << "a"<<i <<"="<<a[i]<<endl;
      i=i+1;
    }   
    
  }

  in_file.close();

}

#include <stdio.h>
#include <dirent.h>
#include <sys/types.h>

int main()
{
    
    
  DIR* d=opendir(".");
  if(d==NULL)
  {
    
    
    printf("d == NULL");
  }

  struct dirent* entry;
  while((entry=readdir(d))!=NULL)
  {
    
    
    puts(entry->d_name);
  }
  closedir(d);

  return 0;
  
}