Calling Lua From a C Program. Litt's Lua Laboratory: Calling Lua From a C Program(With Snippets)Copyright (C). Steve Litt. Contents. Introduction. From a running C. Lua script. The C program can pass arguments to. Lua script, and the Lua script can pass back a return. The Lua. script can serve to initialize the C program, or the Lua script can. C program. Calling a Lua script from a C program can be daunting without the right. Different computers have different names and locations for. Further complicating things is that with every major version of Lua. Lua from C changes. Much documentation on the. Internet is specific to Lua 5. Likewise, this. documentation is specific to 5. The purpose of this document is to make it easy for you to do simple Lua calls from C programs. Anatomy of a Lua Call. A typical interaction from a C program to a Lua 5. C# Corner Annual Conference 2017 Announced; Must Read: Final Release Version Of Angular 2.0 Launched; Must Read: C# 7.0 is available now as a part of Visual Studio.Open default mail program, create new message with the TO field already filled out. Ultimate Delphi Resource from DelphiBasics. Delphi tips and tricks. Delphi and Pascal source code samples. Free applications and components with. Life After Sector 7G: what happens next in the post-Homer era of my career Create a Lua state variable. Load Lua libraries. Load but don't run the Lua script file. Priming script run to create script's global vars. Pass all arguments to the Lua script on the stack. Run the loaded Lua script. Retrieve the return from the Lua script. Close the Lua state variable. Create a Lua state variable lua. Social snippets: Learn how to use the right tags to make your content stand out when shared in social media streams. There are way too many variables, it seems like everything's a. But there's a method to the madness, and this subsection explains it. Could be cc, or gcc, or something else.- Wall. Show all warnings. You might choose not to insert this until all other errors and warnings have been fixed.- o hello. The name of the finished executable. The name of the C file to compile.- I/path/to/Lua/includes. Every C compiler checks for include files in certain places. But often lua. h, liblua. L/path/to/Lua/libraries. Every C compiler checks for libraries to link in certain. But often the Lua libraries are elsewhere, so you need to tell. Lua. Name. Link in the Lua library. The way you name this library in the compiler's - l option requires some thought and research, which will be explained later in this subsection.- lm. Link in the math library (often not necessary)The Process of Finding the Right Compile Command. Finding the right compile command is a process that looks something like this: Try to compile, no link, no - Wall, no - I. You might get lucky. Find the location of the Lua include files. Using that location, compile, no link, no - Wall. Compile, no link, use - Wall. Find the location and filenames of the Lua library files. Using the location and filenames, compile and link. Test the Executable. Step 1: Try to compile, no link, no - Wall, no - I. Do this: cc - o hello hello. Notice that the - c means . Sometimes it's. not all that clear whether an error or warning comes from compile or. If the preceding command. However, in my case it errored out: slitt@mydesk: ~$ cc - o hello hello. No such file or directoryhello. No such file or directoryhello. No such file or directoryhello. Use your Linux box's locate command to find lua. Make sure that the directory with lua. Now see if that directory contains the other two: slitt@mydesk: ~$ ls /usr/include/lua. OK, that's it. You know you need to add - I /usr/include/lua. Step 3: Using that location, compile, no link, no - Wallcc - o hello hello. I/usr/include/lua. In my case the preceding worked: slitt@mydesk: ~$ cc - o hello hello. I/usr/include/lua. If it hadn't worked, and you'd included all three header files in hello. If it doesn't produce errors or warnings, go on to the next step.. Warnings are often. Once you have no errors or warnings, go on to the next step.. Step 5: Find the location and filenames of the Lua library files. First a word about how the - l compiler option works. The - l. option assumes every library file starts with . Therefore, instead. So you need to find the liblua.* files. Do it as follows: sudo updatedblocate liblua ? Those are the Lua libraries on my computer. If these files had been in /usr/lib/lua, we'd have needed an - L option. Step 6: Using the location and filenames, compile and link. This step differs from step 4 in two ways: We remove the - c so that it will attempt to link. We add - llua. 5. Here we go.. slitt@mydesk: ~$ cc - o hello hello. Wall - I/usr/include/lua. It worked. If it hadn't, we'd have been forced to troubleshoot. Step 7: Test the Executable. So let's run it: slitt@mydesk: ~$ ./hello. In C, calling Lua. This is coming from lua. Back in C againslitt@mydesk: ~$. You haven't seen the code for hello. Summary. Here's how you build a C program that runs a Lua script: Create a Lua state variable lua. You use the Linux locate command to find where those files are, and use that location in a - I compiler option. You always link with liblua, and you use locate commands to find where that library is, and use it in the - l compiler option and if its location isn't in a normal library directory, put its directory in a - L compiler option. Getting Lua- calling C programs to compile and link can be difficult and. To limit the difficulty and frustration, use this process: Try to compile, no link, no - Wall, no - I. You might get lucky. Find the location of the Lua include files. Using that location, compile, no link, no - Wall. Compile, no link, use - Wall. Find the location and filenames of the Lua library files. Using the location and filenames, compile and link. Test the Executable. Call it helloscript. Notice it doesn't have the #!/usr/bin/lua line on top. It doesn't have to because the C Lua interface has a built- in Lua interpreter which the lua. We'll call this program hello. Here's the code: #include < lua. Always include this when calling Lua */#include < lauxlib. Always include this when calling Lua */#include < lualib. Always include this when calling Lua */#include < stdlib. For function exit() */#include < stdio. For input/output */void bail(lua. Here's how it compiles and links on my computer: slitt@mydesk: ~$ cc - o hello hello. Wall - I/usr/include/lua. Do what's needed til it compiles no errors, no warnings, with the - Wall compiler option. It should look like this: slitt@mydesk: ~$ ./hello. In C, calling Lua. This is coming from lua. Back in C againslitt@mydesk: ~$. Study the program. Everything should be pretty obvious except lua. Once you've gotten output like the. By the time you're done. Lua to a C subroutine, and have received back. Tourist Trap Alert. All over the Internet, including on some of the Lua project's own. C. subroutine you do: lua. I saw one guy who took the opportunity to tell the asker . Create this callfuncscript. FORGET THIS AND YOU'RE TOAST */bail(L, . Note that the second lua. Litt Opinion. There are several pieces of example code on the net showing the passing. Lua scripts rather than functions, and those. Lua scripts returning arguments. They do this by, within C. Lua. I've chosen not to. In my opinion the internals of such code is a little hard to understand. I never liked global variables in the first place. Multiple args to the main Lua script require multiple global variables such code becomes quite muddled. Functions are built from the ground up to accept a series of arguments. Now take your callfuncscript. FORGET THIS AND YOU'RE TOAST */bail(L, ! Each Lua script requires only one priming run in order to. C program. In order to fully pass an integer into callfuncscript. If nargs is 0 you'll get. So remember, this lua. There are a few idioms you see over and. Before discussing the idioms, here's the. The Lua Program. Here's the Lua program. As you can see, function tweaktable receives a. The Lua tweaktable() function takes a table. It passes back. a completely different table so there's absolutely no question of the. Start by looking and running the code, and then we'll discuss some of the idioms that make it work..#include < lua. Always include this when calling Lua */#include < lauxlib. Always include this when calling Lua */#include < lualib. Prototype for lua. L. FORGET THIS AND YOU'RE TOAST */bail(L, ! The way you place an empty table on the stack. Each time the numeric argument to lua. Here are the many pushers available: lua. You need to do a pop to stay even. And here are some poppers: lua. When a return value is a table, retrieving the. Assuming the Lua function returned only. C. Here's how you access it: lua. The reason you use - 2 as an arg to. On each iteration, lua. Therefore to keep things in place you need one pop per cycle. On every iteration immediately after lua.
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