weeo weeo - 1 month ago 7
C++ Question

C++ how to read a line with delimiter until the end of each line?

Hi I need to read a file that looks like this...

1|Toy Story (1995)|Animation|Children's|Comedy
2|Jumanji (1995)|Adventure|Children's|Fantasy
3|Grumpier Old Men (1995)|Comedy|Romance
4|Waiting to Exhale (1995)|Comedy|Drama
5|Father of the Bride Part II (1995)|Comedy
6|Heat (1995)|Action|Crime|Thriller
7|Sabrina (1995)|Comedy|Romance
8|Tom and Huck (1995)|Adventure|Children's
9|Sudden Death (1995)|Action


As you can see the type of each movie can vary from 1 type to many...I wonder how could I read those until the end of each line?

I'm currently doing:

void readingenre(string filename,int **g)
{

ifstream myfile(filename);
cout << "reading file "+filename << endl;
if(myfile.is_open())
{
string item;
string name;
string type;
while(!myfile.eof())
{
getline(myfile,item,'|');
//cout <<item<< "\t";
getline(myfile,name,'|');
while(getline(myfile,type,'|'))
{
cout<<type<<endl;
}
getline(myfile,type,'\n');
}
myfile.close();
cout << "reading genre file finished" <<endl;
}
}


the result is not what I want...It looks like:

Animation
Children's
Comedy
2
Jumanji (1995)
Adventure
Children's
Fantasy
3
Grumpier Old Men (1995)
Comedy
Romance


So it doesn't stop at the end of each line...How could I fix this?

Answer

Attempting to parse this input file one field at a time is the wrong approach.

This is a text file. A text file consists of lines terminated by newline characters. getline() by itself, is what you use to read a text file, with newline-terminated lines:

while (std::getline(myfile, line))

And not:

while(!myfile.eof())

which is always a bug.

So now you have a loop that reads each line of text. A std::istringstream can be constructed inside the loop, containing the line just read:

   std::istringstream iline(line);

and then you can use std::getline(), with this std::istringstream with the optional delimiter character overriden to '|' to read each field in the line.

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