Talk:cpp/filesystem/is empty

check if a text file is empty

I am having trouble checking if a text file is empty.

this is what I'm thinking structure wise:

while(fin >> s[i]) {

if(//file is empty) { exit(0); }

else // do stuff

}

re :

You may use something like this

Run this code

#include <filesystem>#include <fstream>#include <iomanip>#include <iostream>#include <string_view>   //! @return true if text file @a file_name is emptybool process_text_file(std::string_viewconst file_name){std::fstream text_file{file_name.data()};   bool is_empty {true};   if(!text_file.is_open()){std::cout<<"ERROR: can't open file: "<<std::quoted(file_name)<<'\n';return is_empty;}   for(std::string line;!text_file.bad()&&!text_file.eof();){std::getline(text_file, line);// process text file line by line...if(!line.empty()){ is_empty =false;// do stuff...std::cout<< line <<'\n';}}   return is_empty;}   int main(){std::cout<<std::boolalpha;using std::operator""sv;   auto test =[](std::string_viewconst file_name, std::string_viewconst text =""){std::fstream file(file_name.data(), std::ios::out);if(!text.empty()) file << text; file.close();std::cout<<"test file: "<<std::quoted(file_name)<<'\n';constbool is_empty = process_text_file(file_name);std::cout<<"is empty: "<< is_empty <<'\n';std::filesystem::remove(file_name);// cleanup! be careful!};   test("/tmp/test0001.txt"); test("/tmp/test0002.txt", "line1\nline2\n"); test("/tmp/test0003.txt", "\n\nline1\n");}

re:

Thanks It works :)!! Layan000 (talk) 06:38, 28 February 2021 (PST)