Input/Output Examples in CS Thinking

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Input/Output.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in CS Thinking.

Concept Recap

The mechanisms by which a program receives data from the outside world (input) and sends results back (output). Input can come from keyboards, files, sensors, or network connections; output can go to screens, files, printers, or other devices.

What goes in and what comes out. Keyboard → program → screen.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Programs are useless without I/O—they transform input into output.

Common stuck point: Input needs validation—users may enter unexpected or invalid values that crash the program.

Sense of Study hint: When handling input, always validate and sanitize what you receive before using it in your program. Check for the correct type, reasonable range, and proper format. When producing output, format it clearly so the user or receiving system can understand and use it.

Worked Examples

Example 1

easy
Identify the inputs and outputs in this program: name = INPUT('What is your name?'). age = INPUT('How old are you?'). OUTPUT 'Hello ' + name + ', you are ' + age + '.'

Solution

  1. 1
    Step 1: Inputs are data the program receives from the user. Here there are two inputs: name and age.
  2. 2
    Step 2: The OUTPUT statement displays a message to the user — this is the program's output.
  3. 3
    Step 3: The program takes two inputs (name and age) and produces one output (a greeting message).

Answer

Inputs: name and age (from user). Output: a personalised greeting message.
Input is data entering a program (keyboard, file, sensor). Output is data leaving a program (screen, file, speaker). Every useful program has at least one input or output.

Example 2

medium
A temperature converter takes a Celsius value as input and outputs the Fahrenheit equivalent. Write pseudocode and identify the input, process, and output.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
A program reads a list of 5 test scores and outputs the average. Identify the inputs, process, and output. What type of validation might you add to the input?

Example 2

hard
Describe three different input devices and three different output devices a computer program might use. For each, give an example of a program that uses it.
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