The next command area = a * a assigns to a new variable area the result of the multiplication of a by a. The result is assigned to a variable with the name a. The first line a = int(input('a = ')) prints a message which tells the user to input the side of the square a, then it reads a text (string) and converts it into an integer (this is called parsing) utilizing the function int(…). We will find out later how we can catch such errors and make the user re-enter a number.
You will receive an error message during the execution of the program (exception).
Try to type in an invalid number, for example " hello". Here is how the program would work for a square with a side equal to 3: This is how we can calculate the area of a square by using a given length of its side a: a = int(input( 'a = ')) squares it) and prints the result of the multiplication. It reads an integer, multiplies it by itself (i.e. Let's take the following program as an example. When using input(…) we can include a prompt to the user to tell them what we want them to enter, for example: size = int(input( 'Enter the size = ')) If it weren't for this conversion, for the program every number will be just text with which we wouldn't be able to do arithmetic operations. To read a user input as an integer, it is necessary to declare a variable and use the built-in functions input (…) to read a text line from the console and int (…) to convert a text value to numerical: num = int(input()) Print(msg) # prints value of a variable Reading User Input in Integer Type It allows us to print the value of a variable as well as to directly print a string or a number: print( 9) # prints a number To print text, numbers, or another result on the screen, we need to call the built-in function print(). In Python, the data type is defined by the value that is assigned and is not explicitly specified when declaring variables (as opposed to C#, Java and C++).
Python coding rectangle area program exercises how to#
Here is how to define a variable, assigning a value to it at the time of declaration:Īfter processing, data is still held in variables (i.e. Each variable in Python has a name and value. Variables are named areas of the computer memory which hold data of a certain type, for example, a number or text. All data is held in the computer memory (RAM) as variables. We know that computers are machines that process data. How to do simple arithmetic operations: addition, subtraction, multiplication, division, string concatenation.How to work with data types and variables, which are necessary when processing numbers and strings.
In this chapter, we are going to become familiar with the following concepts and programming techniques:
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