lesson
Updated 6 days ago · 2 views
Imagine you have a toy box labeled score in your favorite video game. Every time you collect a shiny gold coin, the number inside that box changes!
In programming, a variable is a labeled box that holds a value, and a sequence is a list of code instructions that run in order from top to bottom.
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How do you know what number is inside the box after every single instruction runs?
Tracing Step-by-Step
Tracing means reading code line by line and writing down the value inside each variable after each step.
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On line 2, the computer looks inside the box, finds the number 4, adds 3 to it, and puts the new total of 7 right back in.
What happens if a new line of code gives the box a brand-new number instead of adding to it?
Overwriting vs. Adding
When code gives a variable a new number without using a plus sign, it overwrites (replaces) whatever was inside before.
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If
stars = 10 is followed by stars = 2, the box holds 2, not 12.