std::getline() vs get()

std::getline() and get() are both used for reading input, but they serve different purposes and are used in distinct scenarios.

std::getline()

std::getline() is designed to read an entire line of input, including spaces, until it encounters a newline character (\n) or a specified delimiter. It is typically used for reading strings:

1#include <iostream>
2#include <string>
3
4int main() {
5  std::string input;
6  std::cout << "Please provide input: ";
7  std::getline(std::cin, input);  
8  std::cout << "Input extracted: " << input;
9}

1Please provide input: Hello World
2Input extracted: Hello World

In this example, std::getline() captures the full input line, including spaces.

get()

The get() method is a member function of input streams that reads one character at a time or into a buffer. It is more flexible but also more low-level compared to std::getline():

Reading a Single Character

Here, get() reads a single character from the stream:

1#include <iostream>
2#include <sstream>
3
4int main() {
5  std::istringstream input{"Hello"};
6  char ch;
7  input.get(ch);  
8  std::cout << "Character extracted: " << ch;
9}

1Character extracted: H

Reading Multiple Characters into a Buffer

In this case, get() reads up to three characters into the buffer (leaving space for the null terminator):

1#include <iostream>
2#include <sstream>
3
4int main() {
5  std::istringstream input{"Hello"};
6  char buffer[4];
7  input.get(buffer, 4);  
8  std::cout << "Buffer extracted: " << buffer;
9}

1Buffer extracted: Hel

Key Differences

• Purpose: std::getline() is for reading entire lines, while get() is for reading individual characters or fixed-size buffers.
• Delimiter Handling: std::getline() stops at a newline or a specified delimiter. get() can use a delimiter but doesn’t move past it.
• Flexibility: get() offers more control over reading characters, including using it to peek at characters without extracting them.
• Usage: std::getline() is easier for handling user input and text processing. get() is useful in scenarios requiring precise control over character extraction.

Example Comparison

Here’s a side-by-side example:

1#include <iostream>
2#include <sstream>
3
4int main() {
5  std::string lineInput;
6  std::cout << "Enter a line: ";
7  std::getline(std::cin, lineInput);  
8  std::cout << "Line extracted: "
9    << lineInput << '\n';
10
11  std::istringstream input{"Hello"};
12  char charInput;
13  input.get(charInput);  
14  std::cout << "Character extracted: "
15    << charInput << '\n';
16}

1Enter a line: Hello World
2Line extracted: Hello World
3Character extracted: H

Choose std::getline() for simplicity when working with lines and get() for finer control over character-level input.