Python Programming : String

Beginning to Use Python — Strings
 
At this point, you should feel free to experiment with using the shell ’ s basic behavior. Type some text, in
quotes; for starters, you could type the following:
> > > “This text really won’t do anything”
“This text really won’t do anything”
You should notice one thing immediately: After you entered a quote ( " ), the Python shell changed the
color of everything up to the quote that completed the sentence. Of course, the preceding text is
absolutely true. It did nothing: It didn ’ t change your Python environment; it was merely evaluated by
the running Python instance, in case it did determine that in fact you ’ d told it to do something. In this
case, you ’ ve asked it only to read the text you wrote, but doing this doesn ’ t constitute a change to
the environment.
However, you can see that Python indicated that it saw what you entered. It showed you the text you
entered, and it displayed it in the manner it will always display a string — in quotes. As you learn about
other data types , you ’ ll find that Python has a way of displaying each one differently.

What is a String?
 
A string is one of several data types that exist within the Python language. A data type, as the name
implies, is a category that a particular type of data fits into. Every type of data you enter into a computer
is segregated into one of these data types, whether they be numbers or letters, as is the case in this
scenario. Giving data a type allows the computer to determine how to handle the data. For instance, if
you want the program to show the mathematical equation 1+1 on a screen, you have to tell it that it is
text. Otherwise, the program will interpret the data as a mathematical equation and evaluate it
accordingly.
You ’ ll get more into the different data types and how important it is to define them in a later chapter. For
now however, know that a string is a data type that consists of any character, be it a letter, number,
symbol, or punctuation mark. Therefore, the following are all examples of strings:
“ Hello, how are you? ”
“ 1+1 ”
“ I ate 4 bananas ”
“ !@#$%^ & *() ”

Why the Quotes?
 
When you type a string into Python, you do so by preceding it with quotes. Whether these quotes are
single ( ' ), double( '' ), or triple( " " " ) depends on what you are trying to accomplish. For the most part, you
will use single quotes, because it requires less effort (you do not need to hold down the Shift key to
create them). Note, however, that they are interchangeable with the double and even triple quotes.
Try typing in some strings. After you type in each sentence, press the Enter key to allow Python to
evaluate your statement.

Entering Strings with Different Quotes
 
Enter the following strings, keeping in mind the type of quotes (single or double) and the ends of lines
(use the Enter key when you see that the end of a line has been reached):
> > > “This is a string using a double quote”
‘This a string using a double quote’
> > > ‘This is a string with a single quote’
‘This is a string with a single quote’
> > > “””This string has three quotes
look at what it can do!”””
‘This string has three quotes\nlook at what it can do!’
> > >
In the preceding examples, although the sentences may look different to the human eye, the computer
is interpreting them all the same way: that is, as a string. There is a true purpose to having three
different quoting methods, which is described next.