File input using ifstream in C++ - Mini Project: Build & Apply

File input using ifstream

📖 Scenario: You have a text file named data.txt that contains a list of names, one per line. You want to read these names into your C++ program to process them.

🎯 Goal: Build a simple C++ program that reads all names from data.txt using ifstream and stores them in a vector.

📋 What You'll Learn

Create an ifstream object to open data.txt

Check if the file opened successfully

Read each line (name) from the file into a std::string

Store all names in a std::vector<std::string>

Print all names after reading

💡 Why This Matters

🌍 Real World

Reading data from files is common in many programs, such as loading user lists, configuration settings, or logs.

💼 Career

Understanding file input with <code>ifstream</code> is essential for software developers working with data files, system utilities, or any application that processes external data.

1

Create an ifstream object to open the file

Write a line of code to create an std::ifstream object named inputFile that opens the file "data.txt".

C++

# Your code here

Need a hint?

Use std::ifstream followed by the variable name and the filename in parentheses.

2

Check if the file opened successfully

Add an if statement to check if inputFile is open. If not, print "Failed to open file." and return 1.

C++

#include 
#include 
#include 
#include 

int main() {
    std::ifstream inputFile("data.txt");
    // Check if file opened
    
    // Your code here

    return 0;
}

Need a hint?

Use inputFile.is_open() to check if the file opened.

3

Read each line from the file into a vector

Declare a std::vector<std::string> named names. Use a std::string variable line and a while loop with std::getline(inputFile, line) to read each line and add it to names.

C++

#include 
#include 
#include 
#include 

int main() {
    std::ifstream inputFile("data.txt");
    if (!inputFile.is_open()) {
        std::cout << "Failed to open file." << std::endl;
        return 1;
    }
    // Create vector and read lines
    
    // Your code here

    return 0;
}

Need a hint?

Use std::getline inside a while loop to read each line.

4

Print all names read from the file

Use a for loop with const std::string& name to iterate over names and print each name on its own line.

C++

#include 
#include 
#include 
#include 

int main() {
    std::ifstream inputFile("data.txt");
    if (!inputFile.is_open()) {
        std::cout  names;
    std::string line;
    while (std::getline(inputFile, line)) {
        names.push_back(line);
    }
    // Print all names
    
    // Your code here

    return 0;
}

Need a hint?

Use a range-based for loop to print each name.