User:Legend26/Test

• Work in progress. When it's done I'll release it.
• If you find something wrong, have some edit to make, or a way to make it easier to read, go ahead and edit this. It's a wiki after all.
• Article will be named "Beginner's Guide to String Patterns" when finished or something similar.

What are String Patterns?

String patterns are, in essence, just strings. What makes them different from ordinary strings then, you ask? String patterns are strings that use a special combination of characters. These characters combinations are generally used with functions in the string library such as 'string.match' and 'string.gsub' to do special things with strings. For instance, with string patterns you can do something like this:

local s = "I am a string!"
for i in string.gmatch(s, "[^%s]+") do --Where "[^%s]+" is the string pattern.
    print(i)
end

Output:
I
am
a
string!

But what makes the code above so cool? Perhaps you've wanted to make a list of people without using a table, or maybe you need to parse a string. String patterns can help do this!

The Basics of String Patterns

As said before, string patterns are strings that look a little different and are used for a different purpose than what strings are usually used for. Here we will look at the basics of just what make a string pattern up. Here we will look at just what the different parts of a string pattern mean.

Character Classes

Character classes in string patterns stand for a range or set of characters. Let's look at the classes listed below.

• %a

• This character class represents all letters no matter if they're lowercase or uppercase.
• Some examples are: 'a', 'd', 'F', and 'G'.

• %l

• This character class represents all lowercase letters.
• Some examples are: 'a', 'd', 'f', and 'g'.

• %u

• This character class represents all uppercase letters.
• Some examples are: 'A', 'B', 'D', and 'Z'.

• %p

• This character class represents all punctuation characters.
• Some examples are: ".", "?", "+", and "/".

• %w

• This character class represents all alphanumeric letters.

• This means that this class encompasses both letters and numbers.

• Some examples are 'A', 'f', '3', and '7'.

• %s

• This character class represents all space characters.
• Some examples are ' ', '\n', and '\r'

• %c

• This character class represents all control characters.
• Control characters are characters with an ASCII code below 32 and also ASCII code 127
• Control characters are all non-printing meaning that they don't represent a symbol representation.

• %x

• This character class represents all hexadecimal (Base 16) characters.
• Some examples are '21' which represents '!' and '5A' which represents 'Z'

• %z

• This character class represents the character '\0'.
• This character is commonly referred to as NUL.

• The dot character class

• This class is represented by a single dot '.'
• This class represents all characters, every single one.
• Unlike the others, it is not preceded by a '%' sign.

As you can see, each of the character classes are used to represent a set of characters. Now let's look at some just some of the many things we can do with just these character classes.

Examples

A common way of using these string patterns are using them with string functions. Here's an example:

Example

string = "12:47"
for i in string.gmatch(string, "%p") do 
print(p)
end

Output:
>":" --as you can tell, the ":" (colon) character is the only punctuation character there is in the string!

Also, you can captures to find string information.

Example

string = "Twenty one = 21"

_, _, a, b = string.find(string, "(%a+%s%a+)%s=%s(%d+)" --see how I used parenthesis to designate my captures? "a" is the first capture, and "b" is the second capture.

print(a, b)

Output:
>"Twenty one 21"

See also

• String Manipulation