Lua Programming/stringlib
Facilities edit
string.byte edit
string.char edit
string.dump edit
string.find edit
string.format edit
string.gmatch edit
string.gsub edit
string.len edit
Usage edit
string.len(STRING)
Description edit
The string.len function returns the length of the string argument.
print (string.len("Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch")) -- Returns 58
Embedded nul characters edit
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 edit
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 edit
string.match edit
string.rep edit
string.reverse edit
Usage edit
string.reverse(STRING)
Description edit
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 edit
Usage edit
string.sub(STRING, STARTPOS [, ENDPOS])
Description edit
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 edit
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 edit
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 edit
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"