Using cin for input in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is cin used for in C++?

cin is used to get input from the user through the keyboard.

beginner

How do you read an integer value from the user using cin?

Use cin >> variableName; where variableName is an integer variable.

intermediate

What happens if the user enters a non-integer value when reading an integer with cin?

cin will fail to read the input and set an error state. The variable will not change.

beginner

How can you read multiple values in one line using cin?

You can chain extractions like cin >> var1 >> var2 >> var3; to read multiple inputs separated by spaces.

beginner

What header file must be included to use cin?

You must include <iostream> to use cin in your program.

Which header file is required to use cin in C++?

A <cstdio>

B <cmath>

C <string>

D <iostream>

cin is part of the iostream library, so you must include <iostream>.

What does the operator >> do when used with cin?

A Compares two values

B Outputs data to the screen

C Extracts input from the user

D Assigns a value to a variable

The >> operator extracts input from the user when used with cin.

How do you read two integers from the user in one line?

A cin >> a >> b;

B cin << a << b;

C cin >> a, b;

D cin << a, b;

You chain the extraction operator: cin >> a >> b; reads two integers.

What happens if the user enters a letter when cin expects an integer?

A cin crashes the program

B cin fails and sets an error state

C cin ignores the input and waits

D cin converts the letter to zero

cin fails to read and sets an error state if input type does not match.

Which of these is the correct way to declare a variable and read input into it?

A int age; cin >> age;

B cin >> int age;

C int age = cin >>;

D cin age >> int;

You declare the variable first, then use cin >> variable; to read input.

Explain how to use cin to get input from a user in a C++ program.

Think about the steps from including the right file to reading the value.

Describe what happens internally when you use cin >> variable; and the user types input.

Imagine how the program listens and processes what you type.