Strings and %-letter variables? - Developers

I dont really know how to phrase this but I've seen things in strings that are a percent sign and then what appears to me as a random letter and I have never seen this before. It seems to stand in for a variable but is a completely alien concept to me as to how I can use this to benefit my lua coding. So I would really like someone who understands this to point me in the right direction or explain it, I would be very thankful. A paraphrased example based off something I found in the TTT health station entity [code] Damagelog( Format( "%a damaged %b for %c dmg"), dmginfo:GetAttacker(), dmginfo:GetDamage() ) [/code]

It's not random. [t]http://i.imgur.com/OeJgpHz.png[/t] The code you posted will never work. [editline]15th July 2014[/editline] string.format = Format [url]http://wiki.garrysmod.com/page/Global/Format[/url]

They stand for various format flags - consider [url=http://www.cplusplus.com/reference/cstdio/printf/]printf[/url] It makes displaying data in a human-friendly manner simpler. [code]x = string.format( "%s was killed by %s with %s", victim:Nick( ), killer:Nick( ), weapon:GetClass( ) )[/code] Rather than concatenating a lot of text. You can also do interesting things with numbers, like displaying to a certain place, customized padding, if it should pad with 0s or spaces, if it should be displayed in hex, octal, or scientific, etc. There's other specialized ones, like %q, which escapes and wraps the input in quotes, which is handy. [code]pl:SendLua( string.format( "RunSomeFunction( %q )", user_input_here ) )[/code] It becomes considerably harder to escape that than just piping the text in with %s. There's other patterns when regarding os.date or patterns with find, match, gsub, and gmatch, but that's another thread.

it's also a lot more efficient than using .. for concatenation my favorite use for it is printing floats with certain amounts of digits [lua] net.Receive("w/e", function(len) print(string.format("%u bits (%.2f kb) received", len, len/8/1024)) end)[/lua]

It also makes re-using strings easier. [code] local F_REC_MSG = "%u bits (%.2f kb) received" ... print( F_REC_MSG:format( len, len / 8 / 1024 ) )[/code] Which is even handier with sql. [code] Q_INSERT_PLAYER = [[CALL gmod_insert_player_command( %q, %q );]] ... handle:Query( Q_INSERT_PLAYER:format( cl:SteamId( ), net.ReadString( ) ) )[/code] It might be a micro-optimization since strings are cheap and would be on the stack anyways, but it looks nicer to me.

[QUOTE=Robotboy655;45392297]It's not random. [t]http://i.imgur.com/OeJgpHz.png[/t] The code you posted will never work. [editline]15th July 2014[/editline] string.format = Format [url]http://wiki.garrysmod.com/page/Global/Format[/url][/QUOTE] This is what I wanted, I know that code wont work because I forgot the actual letters used. But this definitely looks cool and useful rather than: [code] print( ply1 .. " was hurt by " .. ply2 ) [/code]

Strings are kind-of a controversial subject with lua. I recommend you reading up on them so you fully understand what and how to use the various methods of string concatenation and other methods efficiently.