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https://github.com/hparker/embedding-lua-in-c-by-example
Here is a series of short C snippets to learn how to embed Lua in your C program
https://github.com/hparker/embedding-lua-in-c-by-example
Last synced: 6 days ago
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Here is a series of short C snippets to learn how to embed Lua in your C program
- Host: GitHub
- URL: https://github.com/hparker/embedding-lua-in-c-by-example
- Owner: HParker
- Created: 2020-09-25T01:01:04.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2020-09-26T08:23:48.000Z (about 4 years ago)
- Last Synced: 2024-12-11T14:09:14.449Z (15 days ago)
- Language: C
- Homepage: http://words.hparker.io/embedding-lua-in-c-by-example
- Size: 1.95 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
Awesome Lists containing this project
README
Here is a series of short C snippets to learn how to embed Lua in your C program.
You can find all the scripts together in one file in `embeddingLua.c` and build the project with
You can build and run the project by running:
- `git clone [email protected]:HParker/embedding-lua-in-c-by-example.git`
- `make`
- `./a.out`
# Run a string of Lua code
```c
#include
#include
#include
#include
int main() {
// setup lua
lua_State *L = luaL_newstate();
luaL_openlibs(L);
// Run a lua string
luaL_dostring(L, "print(\"hello from lua\")");
}
```
# Run a file of Lua code
```c
#include
#include
#include
#include
int main() {
// setup lua
lua_State *L = luaL_newstate();
luaL_openlibs(L);
// run a lua file
luaL_dofile(L, "hello.lua");
}
```
# Get a number from Lua
```c
luaL_dostring(L, "x = 10");
lua_getglobal(L, "x");
int x = (int)lua_tonumber(L, -1);
printf("x = %i\n", x);
```
# Get a string from Lua
```c
luaL_dostring(L, "string = 'hi there'");
lua_getglobal(L, "string");
const char * string = lua_tolstring(L, -1, NULL);
printf("string = '%s'\n", string);
```
# Get a table field from Lua
```c
luaL_dostring(L, "table = { key = 123 }");
lua_getglobal(L, "table");
lua_getfield(L, -1, "key");
int key = (int)lua_tonumber(L, -1);
printf("key = %i\n", key);
```
# Call Lua function from C
```c
luaL_dostring(L, "function foo() print(\"Hello from foo method\") end");
lua_getglobal(L, "foo");
if (lua_isfunction(L, -1)) {
// V number of arguments
// | V number of results
int status = lua_pcall(L, 0, 0, 0);
// status can be LUA_OK, LUA_ERRRUN, LUA_ERRMEM, or LUA_ERRERR
if (status != LUA_OK) {
printf("Something went wrong when calling the lua function\n");
} else {
int result = (int)lua_tonumber(L, -1);
printf("result = %i\n", result);
}
} else {
printf("function `foo` was not found or was not a function\n");
}
```
# Calll lua function with a return value from C
```c
luaL_dostring(L, "function foo() return 456 end");
lua_getglobal(L, "foo");
if (lua_isfunction(L, -1)) {
// V number of arguments
// | V number of results
int status = lua_pcall(L, 0, 1, 0);
// status can be LUA_OK, LUA_ERRRUN, LUA_ERRMEM, or LUA_ERRERR
if (status != LUA_OK) {
printf("Something went wrong when calling the lua function\n");
} else {
int result = (int)lua_tonumber(L, -1);
printf("result = %i\n", result);
}
} else {
printf("function `foo` was not found or was not a function\n");
}
```
# Call a lua function with arguements from C
```c
luaL_dostring(L, "function square(x) return x * x end");
lua_getglobal(L, "square");
if (lua_isfunction(L, -1)) {
// V number of arguments
// | V number of results
lua_pushnumber(L, (lua_Number)5);
int status = lua_pcall(L, 1, 1, 0);
// status can be LUA_OK, LUA_ERRRUN, LUA_ERRMEM, or LUA_ERRERR
if (status != LUA_OK) {
printf("Something went wrong when calling the lua function\n");
printf("Error: %s \n", lua_tostring(L, -1));
lua_pop(L, 1);
} else {
int doubled = (int)lua_tonumber(L, -1);
printf("doubled = %i\n", doubled);
}
} else {
printf("function `square` was not found or was not a function\n");
}
```
# Expose a C function to Lua
```c
#include
#include
#include
#include
int basicCFunc(lua_State * L) {
printf("This is my c function called from lua\n");
return 0; // number of results
}
int main() {
// setup lua
lua_State *L = luaL_newstate();
luaL_openlibs(L);
lua_register(L, "basicCFunc", basicCFunc);
luaL_dostring(L, "basicCFunc()");
}
```
# Expose a C function to Lua that returns a value
```c
#include
#include
#include
#include
int returningCFunc(lua_State * L) {
lua_pushnumber(L, 678); // result
return 1; // number of results
}
int main() {
// setup lua
lua_State *L = luaL_newstate();
luaL_openlibs(L);
// expose a function to lua that returns a value
lua_register(L, "returningCFunc", returningCFunc);
luaL_dostring(L, "returnedFromC = returningCFunc()");
lua_getglobal(L, "returnedFromC");
int returnedFromC = (int)lua_tonumber(L, -1);
printf("returned from c = %i\n", returnedFromC);
}
```
# Expose a C function to Lua that takes one arguments
```c
#include
#include
#include
#include
int argumentCFunc(lua_State * L) {
lua_pushnumber(L, lua_tonumber(L, 1) + 1); // result
return 1; // number of results
}
int main() {
// setup lua
lua_State *L = luaL_newstate();
luaL_openlibs(L);
lua_register(L, "argumentCFunc", argumentCFunc);
luaL_dostring(L, "returnedFromC = argumentCFunc(1)");
lua_getglobal(L, "returnedFromC");
returnedFromC = (int)lua_tonumber(L, -1);
printf("returned from c = %i\n", returnedFromC);
}
```
# Expose a C function to Lua that takes any number of arguments
```c
#include
#include
#include
#include
int variableArgumentCFunc(lua_State * L) {
int n = lua_gettop(L); // number of arguments
float sum = 0.0;
int i;
for (i = 1; i <= n; i++) {
if (!lua_isnumber(L, i)) {
lua_pushliteral(L, "incorrect argument");
lua_error(L);
}
sum += lua_tonumber(L, i);
}
lua_pushnumber(L, sum); // result
return 1; // number of results
}
int main() {
// setup lua
lua_State *L = luaL_newstate();
luaL_openlibs(L);
lua_register(L, "variableArgumentCFunc", variableArgumentCFunc);
luaL_dostring(L, "returnedFromC = variableArgumentCFunc(1, 2, 3)");
lua_getglobal(L, "returnedFromC");
returnedFromC = (int)lua_tonumber(L, -1);
printf("returned from c = %i\n", returnedFromC);
}
```