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30 lines
1.0 KiB
Plaintext
30 lines
1.0 KiB
Plaintext
Examples from http://www.wellho.net/mouth/1844_Calling-functions-in-C-from-your-Lua-script-a-first-HowTo.html
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The code is very similar, but you'll notice six additions - in the Lua:
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a) We have added a parameter to the call to dothis in the Lua
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b) We have added an assignment to collect a return value from the C
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summat = cstuff.dothis(value)
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c) We have printed out these values
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print ("Values in Lua now",value, summat)
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and in the C:
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d) We have used lua_tonumber to collect a numeric value that was passed from the Lua to the C; you'll note that all such numbers are treated as doubles. The parameter "1" indicates 1 down - i.e. top of - the state stack.
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double trouble = lua_tonumber(L, 1);
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e) We have performed a calculation (representative of something being done in the C code) and pushed the result of this back onto the Lua state stack so that it can be picked up once we have returned from the C to the Lua
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lua_pushnumber(L, 16.0 - trouble);
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f) We have changed return 0 into return 1 to indicate that one result is being returned.
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return 1; }
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