Lua Programming/stringlib

Facilities string.byte string.char string.dump string.find string.format string.gmatch string.gsub string.len Usage string.len(STRING) 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 string.reverse(STRING) 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 string.sub(STRING, STARTPOS [, ENDPOS]) 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 /substring/s 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