CODEWITHSUNDEEP
pythonstringfunction
Comtron
Comtron

Reputation: 27

A custom function to return the length of a string

I want to define a function which takes an input from the user, returns the length of the input string and prints this out.

I have the following code:

def str_length(my_string):
    my_string = input("give me a string: ")
    return len(my_string)
print(str_length(my_string))

This code does not work. When I exchange the parameter in the last line to "hello" the code works.

def str_length(my_string):
    my_string = input("give me a string: ")
    return len(my_string)
print(str_length("hello"))

Can anyone explain to me why the first code does not work while the second one works? I am totally confused :-(

Upvotes: 0

Views: 811

Answers (2)

alfandango
alfandango

Reputation: 111

As @UnholySheep pointed out, your function is taking a parameter it doesn't seem to need.

Let's break it down

Def str_length (): # start of function definition
    # promt user for the string and put it in the variable "my _string"
    my_string = input ("give me a string:")
    # return the length of input string 
    return len(my_string)

print(str_length ()) # the function is called inside print () and therefore returns the length of the user input string to print () to be printed on screen.

Upvotes: 1

Mehrdad Pedramfar
Mehrdad Pedramfar

Reputation: 11073

You should define it like this:

def str_length():
    my_string = input("give me a string: ")
    return len(my_string)
print(str_length())

When you call the function with my_string you get NameError because there is no my_string define yet. you define it inside the function. (After you call it). that is the reason.

Thanks to @prashantrana, You can also define your function like this:

def str_length(my_string):
    return len(my_string)

my_string = input("give me a string: ")
print(str_length(my_string))

The difference here is that we get input from user out of the function scope, the pass it to function.

Upvotes: 3

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