Lua analyzes the error handling mechanism when running in C Language

When calling the Lua Script Engine in C language, you must identify and handle script errors.

1. Error Type

There are five Lua errors, corresponding to five macro definitions:

# Define lua_yield1 // thread suspended <br/> # define lua_errrun2 // runtime error <br/> # define lua_errsyntax3 // compilation error <br/> # define lua_errmem4 // memory Allocation Error <br/> # define lua_errerr5 // error that occurs when the error processing function is running

Generally, there are two types of errors: runtime errors and compilation errors.

2. Error Return Method

Whether it is a runtime error or a compilation error, the error information is returned to the top layer of the stack. You can print the specific error information using the following code:

Const char * error = lua_tostring (L,-1); // print the error result <br/> printf ("% s", error); <br/> lua_pop (L, 1 );

3. Which functions need to be added with the error analysis mechanism?

The Lua script engine can be used in two steps (the initialization process is not included here)

Step 1 is Script Loading: some of the following functions

Int lual_loadbuffer (lua_state * l, <br/> const char * buff, <br/> size_t SZ, <br/> const char * Name ); <br/> int lual_loadfile (lua_state * l, const char * filename); <br/> int lual_loadstring (lua_state * l, const char * s ); <br/>/* In fact, these functions are for int lua_load (lua_state * l, <br/> lua_reader reader, <br/> void * data, <br/> const char * chunkname); encapsulation <br/> */

All these functions generate compile-time errors. That is, only compile-time errors can be returned through the return values of these functions.

Step 2 is script execution, and some functions are as follows:

Lua_pcall (lua_state * l, int nargs, int nresults, int errfunc );

This function returns a runtime error.

Like some other functions below, the process of combining functions in step 1 and Step 2 has not changed. These functions are roughly as follows:

Int lual_dostring (lua_state * l, const char * Str); <br/> int lual_dofile (lua_state * l, const char * filename );

You can view the help documentation

4. Error Handling example

The following code processes error handling information and prints error information:

# Include "stdafx. H "<br/> extern" C "{<br/> # include" Lua. H "<br/> # include" lualib. H "<br/> # include" lauxlib. H "<br/>}< br/> void printluaerror (lua_state * l, int serr) <br/>{< br/> If (serr = 0) <br/>{< br/> return; <br/>}< br/> const char * error; <br/> char serrortype [256] = {0 }; <br/> switch (serr) <br/> {<br/> case lua_errsyntax: // compilation error <br/>/* const char * Buf = "mylib. myfun () 2222 "; statements similar to this line can cause compilation errors */<br/> spri Ntf_s (serrortype, sizeof (serrortype), "% s", "syntax error during pre-compilation"); <br/> break; <br/> case lua_errmem: // memory error <br/> sprintf_s (serrortype, sizeof (serrortype), "% s", "memory allocation error"); <br/> break; <br/> case lua_errrun: // runtime error <br/>/* const char * Buf = "my222lib. myfun () "; a statement similar to this line can cause a runtime error. my222lib does not actually have such a library, and the returned value is nil */<br/> sprintf_s (serrortype, sizeof (serrortype ), "% s", "a runtime error"); <Br/> break; <br/> case lua_yield: // thread suspension error <br/> sprintf_s (serrortype, sizeof (serrortype), "% s ", "thread has suincluded"); <br/> break; <br/> case lua_errerr: // an error occurred during error handling <br/> sprintf_s (serrortype, sizeof (serrortype), "% s", "error while running the error handler function"); <br/> break; <br/> default: <br/> break; <br/>}< br/> error = lua_tostring (L,-1); // print the error result <br/> printf ("% s: % s", serrortype, error); <br/> Lua _ Pop (L, 1); <br/>}< br/> int main () <br/>{< br/> lua_state * l = lual_newstate (); <br/> lual_openlibs (l); <br/> const char * Buf = "mylib. myfun () "; // note the call rules <br/> int S = lual_loadstring (L, Buf ); // parse the code and do not execute <br/> const char * error; <br/> If (S = 0) <br/>{< br/> S = lua_pcall (L, 0, lua_multret, 0); <br/> If (s! = 0) <br/>{< br/> printluaerror (L, S ); <br/>}< br/> else <br/> {<br/> printluaerror (L, S ); <br/>}< br/> lua_close (l); <br/> getchar (); <br/> return 0; <br/>}< br/>

7. Error clearing

You can run the int lua_error (lua_state * l); statement to execute a jump command. By default, exit the program, that is, exit (exit_failure );

You can also define the jump function by yourself. This part has not been studied in depth yet.