Learning Python With Program Templates: Prompt, Then Read | by Mike McMillan | May, 2022

Know methods to correctly obtain enter out of your customers

Picture by Stefen Tan on Unsplash

Some of the frequent methods to get information right into a Python program is to have the consumer enter it from the keyboard. There’s a program template that describes methods to implement one of these enter. It’s the Immediate, Then Learn template.

On this article, I’m going to reveal methods to implement this template and methods to correctly obtain enter from customers in order that your program can course of it.

Python gives a perform for receiving information from the keyboard — the enter perform. This perform causes a Python program to pause whereas the consumer enters information into this system after which continues this system when the consumer hits the Enter key.

There are two methods to make use of the enter perform — with out a immediate and with a immediate.

Right here is the syntax template for the enter perform with out a immediate:

variable = enter()

The perform takes no matter information is entered on the keyboard and shops it within the variable on the opposite facet of the task operator.

Listed here are some examples:

identify = enter()
radius = enter()

The issue with utilizing this model of the enter perform is the consumer might not know what information is meant to be entered. The answer to this drawback is to make use of the second model of the perform. Right here is the syntax template for this model:

variable = enter(immediate)

Right here is an instance of this model of the enter perform:

identify = enter("What's your identify? ")
print("Hi there," identify)

Right here is the output from this program:

What's your identify? Ringo Starr
Hi there, Ringo Starr

While you present the consumer with some textual content explaining to them what they speculated to enter, you’re offering a immediate. Offering a immediate when gathering information from customers is a crucial strategy to make your packages user-friendly.

The enter perform returns a string when the consumer completed getting into information into the keyboard. When that’s the information kind you need, there’s no drawback. However in case you are getting into numeric information, you don’t need the variable receiving the information to retailer it as a string.

Let me reveal what occurs when numeric information is entered right into a variable as a string. The next program will get a wage quantity from the consumer after which tries to extend it by 10%. Right here is this system:

wage = enter("Enter your wage: ")
wage = wage * 1.10
print("The brand new, elevated wage is: ",wage)

Right here is the output once I run this program:

Enter your wage: 20000
Traceback (most up-to-date name final):
File “C:UsersmmmcmDocumentspythonprog.py”, line 2, in <module>
wage = wage * 1.10
TypeError: can’t multiply sequence by non-int of kind ‘float’

That is an instance of a data-type mismatch error as a result of I attempted to multiply a string by 1.10. Python can’t try this so it simply prints an error message and stops this system.

The answer to this drawback is to transform the information coming in from the enter perform into the right numeric kind. There are two numeric sorts you’ll be able to convert information into int and float.

As a result of changing information from string to a numeric kind is so frequent, Python gives two built-in capabilities for the conversion, conveniently named int and float.

Here’s a syntax template that describes how these capabilities are used:

variable-name = conversion-function(information)

Nevertheless, to make use of these capabilities with the enter perform, we want a special syntax template:

variable-name = conversion-function(enter(immediate))

Let’s use this template to get numeric information in from the consumer. Right here is an instance that asks the consumer to enter their present wage after which reveals them how a lot they are going to make with a 20% pay improve:

wage = int(enter("What's your wage? "))
print("Your present wage is:", wage)
improve = 1.1
wage = wage * improve
print("Your elevated wage is:", wage)

Notice that the wage is transformed by the int perform after the consumer enters an quantity.

Right here is the output from this program:

What's your wage? 35000
Your present wage is: 35000
Your elevated wage is: 38500.0

Now let’s have the consumer enter the quantity of the rise in order that we are able to see how the float conversion perform works. Right here’s the brand new program:

wage = int(enter("What's your wage? "))
print("Your present wage is:", wage)
improve =
float(enter("What's the % of your improve (10% = 1.10)? "))
wage = wage * improve
print("Your elevated wage is:", wage)

Right here is the output from one run of this program:

What's your wage? 30000Your present wage is: 30000What's the % of your improve (10% = 1.10)? 1.10Your elevated wage is: 33000.0

Now that we all know methods to use the enter perform to collect enter from the consumer, we are able to talk about the Immediate, Then Learn template.

Let’s begin with the pseudocode for this template:

Show a message asking for a given worth
Learn the worth

Listed here are a couple of examples of how we are able to implement this template:

print("Enter your identify: ")
identify = enter()
print("What's your avenue handle? ")
handle = enter()
metropolis = enter("What metropolis do you reside in? ")state = enter("Enter your residence state:")

Right here is yet one more instance:

first = enter("What's your first identify? ")
center = enter("What's your center identify? ")
final = enter("What's your final identify? ")
fullName = first + " " + center + " " + final
print("Your full identify is", fullName)

Right here is the output from one run of this program:

What's your first identify? EdgarWhat's your center identify? AllenWhat's your final identify? Poe
Your full identify is Edgar Allen Poe

It’s strictly not obligatory to offer a immediate for the consumer earlier than requesting their enter, however it’s thought of good interface design to take action. Python makes implementing this template even simpler by giving the programmer the power to place the immediate contained in the enter perform.

In my subsequent article, I’ll be discussing the Choose From Options program template. This template is used to make choices on what code to execute primarily based on some situation or set of situations.

Thanks for studying and please reply to this text or electronic mail me along with your feedback and ideas.

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