How to Resolve the \"Expected Constant Expression Error\" for Array Size in C ?

Expected Constant Expression Error for Array Size

In C , declaring arrays with runtime sizes is not permissible. This error occurs in the line float x[size][2] because the compiler expects the array size to be a constant expression.

Resolution

To resolve this error, one can employ alternative approaches:

1. std::vector: Use a vector of arrays to specify the array size at runtime: std::vector< std::array > x(size);
2. Dynamic Memory Allocation: Utilize dynamic memory allocation using new and delete operators: float (*px)[2] = new float[size][2];.
3. Custom Array Type: Define a custom array type that can be placed within a vector if neither C 11 nor boost is accessible.
4. std::pair: Use a vector of std::pair for a simpler syntax: std::vector< std::pair > x(size);

It's important to note that expected constant expression errors arise when an expression cannot be evaluated at compile-time. For array declarations, using constant expressions ensures the compiler can determine the array's size at compilation.

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