Review: Intro to CS 1

Printing Output

We can output messages onto the screen using the "print" function.​

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To print something onto the screen, we use the following format:

print("Your text goes here")​

Comments

To add comments to our code, we can use the following:

• ​# (hashtag)

• ''' (triple quotations)​

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Comments are ignored when running the program and are a good way to highlight ​anything important about your code.

User Input

We can include user input into our programs.

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To ask for user input, we use the following format:

variable_name = input("Question")​

Casting

Casting allows us to convert from one data type to another.

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For example, we can:

• Convert a string into an integer using int( )

• Convert an integer into a string using str( )

Casting

We can only concatenate strings with strings.​

That is, you will have an error when trying to concatenate, or combine, a string with another data type, such as an integer.​

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It is important to use casting when needed!

Example: print("The area is " + str(area))​

Casting

Also note that you may have to convert user input into an integer data type, especially if you are trying to perform mathematical operations.

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Example:

number = input("Enter a number: )

doubled_number = int(number) * 2​

Conditional Statements

Conditional statements tell the computer to run code if something is true.​

In other words, if a certain condition is true, then the code below will run.

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The format uses indentation.

if <boolean condition is true>:

<execute this code>​

Conditional Statements

We can use "else if" and "else" statements if there are more outcomes.

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if <boolean condition is true>:

<execute this code>

elif <another boolean condition>:

<execute this code>

else:

<execute this code>​​