Python Global Variables

Global Variables

Global Variables

Variables that are created outside of a function are known as global variables.

Global variables can be used by everyone, both inside of functions and outside.

Subject | Subject

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Create a variable outside of a function, and use it inside the function.

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Notice how the variable​ is created outside of the function, but it is being used inside of the function.

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​Example

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What is the global variable?

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What will be displayed when this code is ran?

Global vs Local

If you create a variable with the same name inside a function, this variable will be local, and can only be used inside the function. The global variable with the same name will remain as it was, global and with the original value.

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Create a variable inside a function, with the same name as the global variable

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Notice how the variable​ inside of the function has a different value than the Global variable.

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​Example

Multiple Choice

What is the value GLOBAL variable?

• awesome

• fantastic

• Python is

• myfunc( )

Multiple Choice

What is the value LOCAL variable?

• awesome

• fantastic

• Python is

• myfunc( )

The global Keyword

Normally, when you create a variable inside a function, that variable is local, and can only be used inside that function.

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To create a global variable inside a function, you can use the global keyword.

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If you use the global keyword, the variable belongs to the global scope.

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If the variable is inside of the function and if the variable isn't declared as being global, it is considered local.

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​Example

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When the function is ran, what will be displayed?

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Before the function is ran, what is the GLOBAL value of points?

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Before the function is ran, what is the LOCAL value of points?

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When you try to modify the global variable value inside a function, it will throw UnboundLocalError, because while modifying Python treats points as a local variable, but points is also not defined inside the function myfunc( ). It will need to be declared as a global variable to work properly.

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​Example

Fill in the Blanks

Write the code that needs to be added to line 4 in order for the function to add 1 point to the global variable.

Multiple Choice

Which of the following is...

#defining a local variable

• def superfunc( )

• x = fantastic

• print("Python is" + x)

• superfunc()

Multiple Choice

Which of the following is...

#defining a function

• def superfunc( )

• x = fantastic

• print("Python is" + x)

• superfunc()

Multiple Choice

Which of the following is...

#accessing a local variable

• def superfunc( )

• x = fantastic

• print("Python is" + x)

• superfunc()

Multiple Choice

Which of the following is...

#calling the function

• def superfunc( )

• x = fantastic

• print("Python is" + x)

• superfunc()

Fill in the Blanks

Write the code that needs to be added to line 3 in order for the global variable to work properly.