Reply to thread

Message: <blockquote data-quote="gayan kalhara" data-source="post: 3315052" data-attributes="member: 60168">Part 5 Who Goes There?3.1 Input and Variables Now I feel it is time for a really complicated program. Here it is:print "Halt!"s = raw_input("Who Goes there? ")print "You may pass,", sWhen I ran it here is what my screen showed:Halt!Who Goes there? JoshYou may pass, JoshOf course when you run the program your screen will look different because of the raw_input statement. When you ran the program you probably noticed (you did run the program, right?) how you had to type in your name and then press Enter. Then the program printed out some more text and also your name. This is an example of input. The program reaches a certain point and then waits for the user to input some data that the program can use later. Of course, getting information from the user would be useless if we didn’t have anywhere to put that information andthis is where variables come in. In the previous program s is a variable. Variables are like a box that can store somepiece of data. Here is a program to show examples of variables:a = 123.4b23 = ’Spam’first_name = "Bill"b = 432c = a + bprint "a + b is", cprint "first_name is", first_nameprint "Sorted Parts, After Midnight or",b23And here is the output:a + b is 555.4first_name is BillSorted Parts, After Midnight or SpamVariables store data. The variables in the above program are a, b23, first_name, b, and c. The two basic typesare strings and numbers. Strings are a sequence of letters, numbers and other characters. In this example b23 andfirst_name are variables that are storing strings. Spam, Bill, a + b is, and first_name is are the stringsin this program. The characters are surrounded by " or ’. The other type of variables are numbers.Okay, so we have these boxes called variables and also data that can go into the variable. The computer will see a linelike first_name = "Bill" and it reads it as Put the string Bill into the box (or variable) first_name. Lateron it sees the statement c = a + b and it reads it as Put a + b or 123.4 + 432 or 555.4 into c.Here is another example of variable usage:a = 1print aa = a + 1print aa = a * 2print aAnd of course here is the output:124Even if it is the same variable on both sides the computer still reads it as: First find out the data to store and than find out where the data goes.One more program before I end this chapter:num = input("Type in a Number: ")str = raw_input("Type in a String: ")print "num =", numprint "num is a ",type(num)print "num * 2 =",num*2print "str =", strprint "str is a ",type(str)print "str * 2 =",str*2The output I got was:Type in a Number: 12.34Type in a String: Hellonum = 12.34num is a <type ’float’>num * 2 = 24.68str = Hellostr is a <type ’string’>str * 2 = HelloHelloNotice that num was gotten with input while str was gotten with raw_input. raw_input returns a string while input returns a number. When you want the user to type in a number use input but if you want the user to type in a string use raw_input. The second half of the program uses type which tells what a variable is. Numbers are of type int or float (which 10 Chapter 3. Who Goes There?are short for ’integer’ and ’floating point’ respectively). Strings are of type string. Integers and floats can be worked on by mathematical functions, strings cannot. Notice how when python multiples a number by a integer the expected thing happens. However when a string is multiplied by a integer the string has that many copies of it added i.e. str * 2 = HelloHello.</blockquote>

Verification: Nawa warak dahaya keeyada? (Namaya wadi kireema dahaya)

Top Bottom