Python Program Example Function

Functions Introduction Last lesson I said that we would delve into purposefull programming. That involves user input, and user input requires a thing called functions. What are functions? Well, in effect, functions are little self-contained programs that perform a specific task, which you can incorporate into your own, larger programs. After you have created a function, you can use it at any time, in any place. This saves you the time and effort of having to retell the computer what to do every time it does a common task, for example getting the user to type something in.

Using a function Python has lots of pre-made functions, that you can use right now, simply by 'calling' them. 'Calling' a function involves you giving a function input, and it will return a value (like a variable would) as output. Don't understand?

The official home of the Python Programming Language. Php: The mbstring package adds UTF-8 aware string functions with mb_ prefixes. Python: We assume that os, re, and sys are always imported. Grammar and Execution. You are here: Home ‣ Dive Into Python 3 ‣ Difficulty level: ♦♢♢♢♢ Your First Python Program Don’t bury your burden in saintly silence.

Here is the general form that calling a function takes. Function_name(parameters) See? • Function_name identifies which function it is you want to use (You'd figure.). For example, the function raw_input, which will be the first function that we will use. • Parameters are the values you pass to the function to tell it what is should do, and how to do it.

For example, if a function multiplied any given number by five, the stuff in parameters tells the function which number it should multiply by five. Put the number 70 into parameters, and the function will do 70 x 5. Applemacsoft Drm Converter Keygen Idm there. Parameters and Returned Values - Communicating with Functions Well, that's all well and good that the program can multiply a number by five, but what does it have to show for it? A warm fuzzy feeling? Your program needs to see the results of what happened, to see what 70 x 5 is, or to see if there is a problem somewhere (like you gave it a letter instead of a number). So how does a function show what is does?

Well, in effect, when a computer runs a function, it doesn't actually see the function name, but the result of what the function did. Variables do the exact same thing - the computer doesn't see the variable name, it sees the value that the variable holds. Lets call this program that multiplied any number by five, multiply(). You put the number you want multiplied in the brackets. So if you typed this. A = 'hello' print 'hello' Remember, a variable is just a stored value. To the computer, the variable 'a' doesn't look like 'a' - it looks like the value that is stored inside it.

Functions are similar - to the main program (that is, the program that is running the function), they look like the value of what they give in return of running. A Calculator Program Lets write another program, that will act as a calculator. This time it will do something more adventerous than what we have done before. Rengou Vs Zaft 2 Plus Iso 9000. There will be a menu, that will ask you whether you want to multiply two numbers together, add two numbers together, divide one number by another, or subtract one number from another. Only problem - the raw_input function returns what you type in as a string - we want the number 1, not the letter 1 (and yes, in python, there is a difference.). Luckily, somebody wrote the function input, which returns what you typed in, to the main program - but this time, it puts it in as a number. If you type an integer (a whole number), what comes out of input is an integer.

And if you put that integer into a variable, the variable will be an integer-type variable, which means you can add and subtract, etc. Now, lets design this calculator properly. We want a menu that is returned to every time you finish adding, subtracting, etc. In other words, to loop (HINT!!!) while (BIG HINT!!!) you tell it the program should still run. We want it to do an option in the menu if you type in that number.

That involves you typing in a number (a.k.a input) and an if loop. Lets write it out in understandable English first. START PROGRAM print opening message while we let the program run, do this: #Print what options you have print Option 1 - add print Option 2 - subtract print Option 3 - multiply print Option 4 - divide print Option 5 - quit program ask for which option is is you want if it is option 1: ask for first number ask for second number add them together print the result onscreen if it is option 2: ask for first number ask for second number subtract one from the other print the result onscreen if it is option 3: ask for first number ask for second number multiply! Print the result onscreen if it is option 4: ask for first number ask for second number divide one by the other print the result onscreen if it is option 5: tell the loop to stop looping Print onscreen a goodbye message END PROGRAM Lets put this in something that python can understand. #calculator program #this variable tells the loop whether it should loop or not. # 1 means loop.