A string is a sequence of characters . Strings are basically just words.
I can almost guarantee that you will be using strings in every Python program that you write, so pay careful attention to the following part. Here's how you can use strings in Python:
Using Single Quotes ('). You can specify strings using single quotes such as 'Quote me on this' . All white space i.e. spaces and tabs are preserved as-is.
Using Double Quotes("). Strings in double quotes work exactly the same way as strings in single quotes. An example is "What's your name?" .
Using Triple Quotes (''' or """). You can specify multi-line strings using triple quotes. Also, you can use single quotes and double quotes freely within triple quotes. Examples are
'''This is a multi-line string. This is the first line. This is the second line. "What's your name?," I asked. He said "Bond, James Bond." '''
Escape Sequences. Suppose you want to have a string which contains a single quote ('), how will you specify this string? For example, the string is What's your name?. You cannot specify 'What's your name?' because Python will be confused as to where the string starts and ends. So, you will have to specify that this single quote does not indicate the end of the string. This is done with the help of what is called an escape sequence. You specify the single quote as \' - notice the backslash. Now, you can specify the string as 'What\'s your name?'
Another way of specifying this specific string would be "What's your name?" i.e. using double quotes. Similarly, you have to use an escape sequence for using a double quote itself in a double quoted string. Also, you have to indicate the backslash itself using an escape sequence \\.
What if you wanted to specify a two-line string? One way is to use a triple-quoted string as shown above or you can use an escape sequence for the newline character \n which indicates that a new line is about to start. An example is 'This is the first line.\nThis is the second line.'
Other escape sequences include \r (carriage return), \a (bell), etc. Also, remember that a single backslash at the end of the line indicates that the string is continued in the next line but it does not mean that there is a newline. For example,
"This is the first sentence.\ This is the second sentence."
is equivalent to "This is the first sentence.This is the second sentence."
Raw Strings. If you need to specify some strings where you don't want any special processing such as escape sequences, then you can specify the string as a raw string by prefixing r or R to the string. An example is r"Newlines are indicated by \n.".
Unicode Strings. Unicode is a standard used for internationalization. If you want to write text in your native language such as Hindi or Arabic, then you need to have a Unicode-enabled text editor. If you want to use Unicode strings in Python, you can prefix the string with u or U such as u"This is a Unicode string.". Remember to use Unicode strings when you deal with text files, especially, if it involves text written in languages other than English.
Strings are immutable. This means that once you have created a string, you cannot change it. Although this might seem like a bad thing, it really isn't. We will see why this is not a limitation in the various programs that we see later on.
String literal concatenation. If you place two string literals side by side, they are automatically concatenated by Python. For example, 'What\'s ' "your name?" is automatically converted to "What's your name?" .
There is no separate char data type in Python. There is no real need for it and I am sure you won't miss it.
Remember that single-quoted strings and double-quoted strings are the same - they do not differ in any way.
Always use raw strings when dealing with regular expressions. Otherwise, a lot of backwhacking may be required. For example, backreferences can be referred to as '\\1' or r'\1'.