Thread: extra line while reading from file

My file has these lines.
I try to remove extra line in the end, in notepad/gedit, however, after saving it automatically adds up there.

one
two
three

Code:

void help::read_ref(const char* file_name){
     std::ifstream file_handle;
     file_handle.open(file_name);

     std::string line,name;
     getline(file_handle,line);

     while(!file_handle.eof()){

         if(line[0]=='>'){
             name=line.substr(1,line.length()-1);//taking selected chars
             reference[name]="";
         }

        
       getline(file_handle,line);     
 }
     file_handle.close();

     std::cerr<<"file reading done"<<"\n";

}

//when I print size of map, it comes out to be an extra then what is should be.
std::map<std::String,std::string> ->is my map

on the contrary if I use

Code:

 file_handle >> line;

I get correct number of entries in map.

My doubt: getline, automatically finds \n and in last, it finds a \n, why it doesn't end the iteration?
I have faced this issue many number of times.
Please guide.

Code:

line[0]=='>'

I am making this check, then also, I get a null string as key in my map.

I have printed key with their index, using

Code:

map iterator

.

Originally Posted by deathmetal

My file has these lines.
I try to remove extra line in the end, in notepad/gedit, however, after saving it automatically adds up there.

laserlight, thank you for your reply.
Can you please help me understand this?
eof looks for last empty line, if I am not wrong?

Elysia,
Thank you very much on these points.

Originally Posted by Elysia

>> std::ifstream file_handle;
>> file_handle.open(file_name);
You should learn to use constructors:
std::ifstream file_handle(file_name);

>> file_handle.close();
There is no need to close files manually. They close automatically when they go out of scope. C++ isn't Java.

@Elysia, laserlight:
Thanks much. I got it

Originally Posted by Elysia

eof() checks if the eof flag has been set. That flag is set only after the first read beyond the end of the file.
So your loop, on its last iteration, succeeds (ie eof() return false). Next iteration, you read beyond the file (hence you will get an empty line), and the eof flag gets set.
Next iteration, the loop terminates.