[<< wikibooks] Lua Programming/stringlib
== Facilities ==

=== string.byte ===

=== string.char ===

=== string.dump ===

=== string.find ===

=== string.format ===

=== string.gmatch ===

=== string.gsub ===

=== string.len ===

==== Usage ====

==== Description ====
The string.len function returns the length of the string argument. 

print (string.len("Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch"))  -- Returns 58

===== Embedded nul characters =====
Embedded nul characters do not terminate the string and are also counted by this function.

print (string.len("ab\000cd\000"))  -- Returns 6

===== The length operator can also be used to determine the length of a string =====
The lua programming language provides a length operator, which can also be used to determine the length of a string:

print (#"Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch")  -- Returns 58

=== string.lower ===

=== string.match ===

=== string.rep ===

=== string.reverse ===

==== Usage ====

==== Description ====
The string.reverse function can be used for reversing string and returns the string with its character order reversed:

print (string.reverse("anut fo raj a rof tun A"))  -- A nut for a jar of tuna

=== string.sub ===

==== Usage ====

==== Description ====
The string.sub function returns a substring of the string argument from a start position, and an optional end position.

print (string.sub("cheese salad sandwich",8))  -- position 8 onwards gives us "salad sandwich"
print (string.sub("cheese salad sandwich",1,12)  -- positions 1 to 12 gives us "cheese salad"

===== The start position cannot be omitted, but the end position may be omitted =====
Note that the start position is not optional, so for substrings starting at the first position, a parameter of one must be provided:

-- This does not work
print (string.sub("cheese salad sandwich",,12)  -- we cannot omit the start position
-- To fix this, we must provide a substring position
print (string.sub("cheese salad sandwich",1,12)  -- we want a substring from position 1

==== The end position can be omitted or negative ====
Without an end position, the substring continues to the end of the string:

print (string.sub("cheese salad sandwich",8))  -- position 8 onwards gives us "salad sandwich"

==== String positions may be negative ====
The end position can be negative. A negative value indicates the number of characters from the end, with -1 meaning the last character, -2 meaning the last but one character, etc:

print (string.sub("cheese salad sandwich",-8))  -- start 8 characters from the end gives "sandwich"
print (string.sub("cheese salad sandwich",1,-9))  -- drop " sandwich" to give "cheese salad"

=== string.upper ===