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In & Out

Every program takes something in and sends something out. Learn how to read user input, convert and validate it, handle a login, and read data from a CSV file in the right order.

⏱️ 16 min 🎯 14 activities Teachers Not yet rated Students Not yet rated

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What you'll cover

Talking to a program 💬

Every useful program takes something **in**, does some work, then sends something **out**. Reading data from the user is **input**; showing a result is **output**. Getting this right is the start of every program.

Words to know 🔑

Four ideas run through input and output:

String or number? ⚖️

Input usually arrives as text, even when it looks like a number.

Why convert? 🎯

Why must a number typed by the user usually be converted before a calculation?

  • It is read in as a string, not a number
  • Numbers are too slow to use directly
  • To keep the number secret
  • To change its colour on screen

Match the check 🔗

  • Length check
  • Presence check
  • Range check
  • Pattern check
  • Makes sure a password is long enough
  • Makes sure a field is not left empty
  • Makes sure a value is between two limits
  • Makes sure input follows a set format

Who goes there? 💡

Many programs need to check who you are. A simple authentication routine asks for an ID and a password, then looks them up in a stored list. If both match a record you are let in; if not, access is refused. Passwords should never be shown on screen as they are typed.

Trace the input 📊

An interactive activity.

Kinds of validation ✅

Which THREE are types of input validation?

  • A length check
  • A range check
  • A presence check
  • A colour check
  • A volume check

Reading a CSV 🪜

An interactive activity.

Complete the idea 🧩

A program uses _____ to read from the user and _____ to show a result. Because input arrives as a _____, it is _____ to a number before any calculation. Before using the value, the program should _____ it to check it is sensible.

input output string cast validate delete number file sort close

True or not? 🖍️

An interactive activity.

Match the term 🔀

  • Input
  • Output
  • Cast
  • Authenticate
  • Read data into the program
  • Send a result out to the user
  • Convert a string into a number
  • Check an ID and password to allow access

Which check? 🧭

An interactive activity.

Explain input and output ✍️

An interactive activity.