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Questions and Answers
What is the primary characteristic that defines a variable in programming?
What is the primary characteristic that defines a variable in programming?
Where are global variables typically declared in a program?
Where are global variables typically declared in a program?
What is the scope of a local variable?
What is the scope of a local variable?
What is the lifespan of a global variable in a program?
What is the lifespan of a global variable in a program?
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Which of the following accurately indicates the lifespan of a local variable?
Which of the following accurately indicates the lifespan of a local variable?
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If the same variable name 'x' is used inside a function and outside, where is the local variable 'x' used?
If the same variable name 'x' is used inside a function and outside, where is the local variable 'x' used?
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What would happen if you tried to access a local variable from outside the function where it is declared?
What would happen if you tried to access a local variable from outside the function where it is declared?
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Suppose you have a variable that needs to be updated and accessed from multiple functions in a program. What type of variable should you use?
Suppose you have a variable that needs to be updated and accessed from multiple functions in a program. What type of variable should you use?
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Study Notes
Robotics 2 - Lesson 1: Understanding Global and Local Variables
- The lesson focuses on global and local variables in programming, specifically within Arduino.
- Target: Define variables; identify the difference between global and local variables; create projects using global and local variables in code.
- Variable: A named storage location in memory holding a value. Arduino variables can be of different types (e.g., int, float, char).
- Global Variables: Declared outside any function; accessible by any function in the same file from the declaration point to the end of the program.
- Local Variables: Declared within a function; accessible only within that function from the declaration point to the end of the function.
Key Differences Between Global and Local Variables
- Scope: Global variables are accessible from anywhere within the program, while local variables are restricted to the function they're defined in.
- Lifetime: Global variables exist throughout the entire program's execution. Local variables are created when their function is called and destroyed when it ends.
- Memory: Global variables are stored in a fixed memory location, while local variables are stored on the stack, with memory allocated when the function begins.
Example Code (Illustrating Global Variables)
- Shows
int x=7as a global variable accessible in bothsetup()andloop()functions.
Example Code (Illustrating Local Variables)
- Demonstrates
int x=7declared within theloop()function, with its scope limited to that function.
Activity 1: Understanding Local and Global Variables
- Target: Build and code based on a circuit diagram.
- Materials: Arduino board, resistors, wires, USB cable, breadboard, LEDs (light-emitting diodes).
- Example code provided for the activity includes global variables for LED pins (e.g.,
int redLED = 11).
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Description
This lesson delves into the concepts of global and local variables in the context of Arduino programming. You'll learn how to define these variables, distinguish their differences, and apply them in various coding projects.
