Week 7: Variables and naming

A variable is a named box that holds a value. In C, a variable name cannot contain spaces, and it cannot start with a digit. To join words in a name, programmers often use an underscore, as in total_score. You give a variable its value with =. This week you learn to type both symbols on the US English layout.

What you will learn

On the US English layout:

• _: the - key with Shift. Press Shift with the opposite pinky, and press the - key with your right pinky.
• =: the = key, with your right pinky.

Two examples: total_score and player_name are both clear variable names. The underscore takes the place of a space, so the words stay readable.

Technique tips

• When you type the underscore, press Shift with the opposite pinky first, then reach to the - key with your right pinky.
• Use lowercase letters and separate words with underscores. Names starting with a capital letter are also valid, but aim for one style this week.
• Type the value right after the equals sign, as in total_score = 0. Keeping the name and value on one line makes the assignment easy to check.
• Look at the screen. Make sure each underscore sits between two words, not at the end of a name by mistake.

Lessons

1. Lesson 1, learn (10 to 15 minutes): Watch the _ and = symbols on the keyboard demo. Type each one five times.
2. Lesson 2, practice (10 to 15 minutes): Type names such as total_score, player_name and best_score. Check the underscores in each name one by one.
3. Lesson 3, review (10 to 15 minutes): Take the two-minute test with variable names and assignments. Save your result and practice the names you got wrong.

This week’s goal

This week’s target is 16 WPM and 92% accuracy. Finishing the week’s lessons earns you 1 star. Reach 92% accuracy for 2 stars, and also reach 16 WPM for 3 stars. One wrong underscore makes the program look for a name that does not exist, so type slowly and carefully.