In the previous example, you have seen that python can take no parameter and return some value. In this example, you will learn that a function can take some parameter and output the results without returning the value.
Python Program To Reverse a String
In this example, we will accept a string as parameter and then reverse the string and print the output to the console. The function does not return anything.
## Program to reverse a string my_string = "Great Country!" # Function Definition def reverse_string(s): for i in range(len(s)-1, -1, -1): print(s[i], end= " ") # Function Call reverse_string(my_string)
There are a few things worth mentioning here. The function use the
len() function which returns the length of the string. The
len(s)-1 gives the index of the last character of the
my_string.The index of first character is 0.
== RESTART: C:/Python_projects/Functions/Parameter_No_Return.py == ! y r t n u o C t a e r G >>>
Lets understand why
range(len(s)-1, -1, -1) is going to work. The range function starts with
len(s)-1 and goes up to
-1. But it does not include
-1 because range does not include the upper limit. Therefore, all characters starting with
12(because there are 13 characters in the string) to
0 are printed in reverse order.
Note that the last
-1 in the
range() function indicate that the function is decrementing. In the next article, we will discuss about functions that do take parameters and also return a value.