How to prevent warning: ISO C++ forbids variable length array ‘nodes’ [-Wvla]

Question

I get this warning for these two lines of code:

 const int entityNumber = materialNames.size();
 SceneNode* nodes[entityNumber];

I thought declaring entityNumber as const would fix this. (It did in a previous version when entity number was just a value I set myself) however it doesn't appear that this works. As you can tell I am quite new to c++, so sorry if this is a stupid question.

If materialNames.size() can't be determined at compile-time, then the compiler can't preallocate the memory for the array. — Dan Lecocq
– Dan Lecocq, Commented Mar 29, 2013 at 21:56

Dan Lecocq · Accepted Answer · 2013-03-29 21:59:57Z

2

You should probably make a std::vector, which is a dynamic-length array, but with a lot of support for common operations:

// This reserves space for all the nodes you'll store
std::vector<SceneNode> nodes(materialNames.size());

answered Mar 29, 2013 at 21:59

Dan Lecocq

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n. m. could be an AI · Accepted Answer · 2013-03-29 21:58:50Z

1

Use std::vector instead of legacy arrays.

answered Mar 29, 2013 at 21:58

n. m. could be an AI

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