Python Programming (Defining Your Own Functions)

University:
California State University, Chico
Course:
CSED 590 | Software Design, Data Structures, and Algorithms
Academic year:

2024
Views:

0

Pages:

4
Author:

Sanchit Kumar

Python programming Defining Your Own Functions We can define our own functions in Python and reuse them throughout the program. The syntax for defining a function is as follows: def functionName(parameters): code detailing what the function should do return [expression] There are two keywords here, def and return. def tells the program that the indented code from the next line onwards is part of the function. return is the keyword that we use to return an answer from the function. There can be more than one return statements in a function. However, once the function executes a return statement, the function will exit. If your function does not need to return any value, you can omit the return statement. Alternatively, you can write return or return None. Let us now define our first function. Suppose we want to determine if a given number is a prime number. Here’s how we can define the function using the modulus (%) operator we learned in Chapter 3 and the for loop and if statement we learned in Chapter 6. def checkIfPrime (numberToCheck): for x in range(2, numberToCheck): if (numberToCheck%x == 0): return False return True In the function above, lines 2 and 3 uses a for loop to divide the given parameter numberToCheck by all numbers from 2 to numberToCheck - 1 to determine if the remainder is zero. If the remainder is zero, numberToCheck is not a prime number. Line 4 will return False and the function will exit. If by last iteration of the for loop, none of the division gives a remainder of zero, the function will reach Line 5, and return True. The function will then exit. To use this function, we type checkIfPrime(13) and assign it to a variable like this answer = checkIfPrime(13) Here we are passing in 13 as the parameter. We can then print the answer by typing print(answer). We’ll get the output: True.

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