How to Fix the \'Expected Constant Expression\' Error When Declaring Arrays in C ?

Resolving "Expected Constant Expression" Error for Array Size

Consider the following C code:

<code class="cpp">int count = 0;
float sum = 0;
float maximum = -1000000;

std::ifstream points;

int size = 100;
float x[size][2]; // <p>This code raises an "expected constant expression" error when declaring the array x. This error occurs because C   requires non-static array sizes to be known at compile time.</p>
<p><strong>Solution Using Vectors</strong></p>
<p>To resolve this issue, we can use a C   vector instead of an array:</p>
<pre class="brush:php;toolbar:false"><code class="cpp">std::vector<:array>> x(size);</:array></code>

Solution Using new

Another approach involves dynamically allocating the array using the new operator:

<code class="cpp">float (*px)[2] = new float[size][2];</code>

Alternative Solutions

• Use Boost: If you have access to the Boost library, you can use boost::array instead of std::array.
• Define Custom Array Type: Define a custom array type that supports dynamic sizing and use it in a vector.

Considerations for Non-C 11 Compilers

If you don't have C 11 support, use the following techniques:

• Use an identity template to simplify the syntax when using new.
• Use a vector of std::pair as an alternative to the vector solution mentioned earlier.

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