File input using ifstream in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file named "data.txt" for reading.

C++

#include <fstream>
#include <iostream>

int main() {
    std::ifstream file;
    file.[1]("data.txt");
    if (!file) {
        std::cout << "Failed to open file." << std::endl;
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

Awrite

Bopen

Cread

Dclose

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'close' instead of 'open' to open the file.

Trying to use 'read' or 'write' directly to open the file.

The open function is used to open a file with ifstream.

2fill in blank

medium

Complete the code to read a single word from the file into the variable 'word'.

C++

#include <fstream>
#include <iostream>
#include <string>

int main() {
    std::ifstream file("data.txt");
    std::string word;
    if (file >> [1]) {
        std::cout << "Read word: " << word << std::endl;
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

Adata

Binput

Cfile

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to read into 'input' or 'file' which are not variables for storing the word.

Using 'data' which is not declared.

We read into the variable word using the extraction operator.

3fill in blank

hard

Fix the error in the code to properly check if the file was opened successfully.

C++

#include <fstream>
#include <iostream>

int main() {
    std::ifstream file("data.txt");
    if ([1]) {
        std::cout << "File opened successfully." << std::endl;
    } else {
        std::cout << "Failed to open file." << std::endl;
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

Afile.is_open()

Bfile

C!file

D!file.is_open()

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!file' which checks if the file failed to open, but logic is reversed.

Using '!file.is_open()' which is true when file is not open.

The is_open() method returns true if the file is open.

4fill in blank

hard

Fill both blanks to read all words from the file and print them.

C++

#include <fstream>
#include <iostream>
#include <string>

int main() {
    std::ifstream file("data.txt");
    std::string [1];
    while (file >> [2]) {
        std::cout << [2] << std::endl;
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

Aword

Bfile

Cinput

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for declaration and reading.

Using 'file' as a variable to store words.

The variable word is used to store each word read from the file.

5fill in blank

hard

Fill all three blanks to open a file, read integers, and sum them.

C++

#include <fstream>
#include <iostream>

int main() {
    std::ifstream [1]("numbers.txt");
    int [2], sum = 0;
    while ([1] >> [2]) {
        sum += [2];
    }
    std::cout << "Sum: " << sum << std::endl;
    return 0;
}

Drag options to blanks, or click blank then click option'

Afile

Bnum

Dnumber

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the file stream in declaration and reading.

Using 'number' instead of 'num' for the integer variable.

The ifstream object is named file, and the integer variable is num. The same file is used to read integers.