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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?
- A conditional statement used for decision-making in a program.
- A named storage location in memory that can hold a value. (correct)
- A function that executes a specific task.
- A constant value that cannot be changed.
Where are global variables typically declared in a program?
Where are global variables typically declared in a program?
- Outside of any function, typically at the beginning of a program. (correct)
- Within the program's conditional statements.
- Only within the main loop function of the program.
- Inside specific functions where they are used.
What is the scope of a local variable?
What is the scope of a local variable?
- Accessible only within the function where it is declared. (correct)
- Accessible in all functions except the one where it is declared.
- Accessible in all the loop functions.
- Accessible throughout the entire program.
What is the lifespan of a global variable in a program?
What is the lifespan of a global variable in a program?
Which of the following accurately indicates the lifespan of a local variable?
Which of the following accurately indicates the lifespan of a local variable?
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?
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?
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?
Flashcards
What is a variable?
What is a variable?
A named storage location in memory that can hold a value. Variables in Arduino can have different types (e.g., int, float, char, etc.).
What is a Global variable?
What is a Global variable?
Global variables are declared outside of any function and can be accessed by any function within the same file. They are available throughout the program's lifetime.
What is a Local variable?
What is a Local variable?
Variables declared inside a function. They are only accessible within that function and exist only as long as the function is running.
What is 'Scope' in terms of variables?
What is 'Scope' in terms of variables?
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Explain 'Lifetime' of variables.
Explain 'Lifetime' of variables.
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Give an example of a Global variable.
Give an example of a Global variable.
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Give an example of a Local variable.
Give an example of a Local variable.
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What is the key difference between Global and Local variables?
What is the key difference between Global and Local variables?
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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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