CODEWITHSUNDEEP
c++text-files
notexactly
notexactly

Reputation: 1018

(C++) Why are additional blank lines in the text file not being counted?

I have created this function to return the number of lines in a text file:

int numberOfLinesInFile(string dataFile){            
    ifstream inputFile;
    inputFile.open("data.txt");
    int numberOfLines, data;

    while(!inputFile.eof()){
        inputFile >> data;
        numberOfLines++;
    }

    cout << "Number of lines: " << numberOfLines << endl;
    inputFile.close();
    return numberOfLines;
}

An interesting thing that I noticed is that the function counts the number of the non-blank lines (and an additional blank line at the end) correctly, but the additional blank lines are not being counted. For example, if this is my file:

234
453
657

then the function returns 4, since there are four lines in the text file. However, if my file contains more than one blank line at the end:

234
453
657

the function returns 4 again.

Why is this happening? Does this have to do with the eof instruction?

EDIT:

Okay, thank you @MikeCAT for making me understand where the problem was. Based on @MikeCAT's answer, I changed the while loop as:

while(!inputFile.eof()){
        if(inputFile >> data)
            numberOfLines++;
        else{
            cout << "Error while reading line " << numberOfLines + 1 << "!" << endl;
        }
}

I was incrementing numberOfLines without making sure that the line was actually read.

Upvotes: 1

Views: 165

Answers (1)

MikeCAT
MikeCAT

Reputation: 75062

Firstly, you are doing numberOfLines++; after inputFile >> data; without checking if the reading is successful. This is bad and lead to an extra counting.

Secondly, inputFile >> data; reads integer and skip whitespace characters before integers.

To avoid these problems, you should use std::getline() to count lines.

Also don't forget to initialize numberOfLines.

int numberOfLinesInFile(string dataFile){            
    ifstream inputFile;
    inputFile.open("data.txt");
    int numberOfLines = 0;
    std::string data;

    while(std::getline(inputFile, data)){
        numberOfLines++;
    }

    cout << "Number of lines: " << numberOfLines << endl;
    inputFile.close();
    return numberOfLines;
}

Upvotes: 2

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