When using the ExprTk library (which is a C++ expression parsing and evaluation library), you may encounter performance issues or even crashes when large or complex expressions are compiled. To limit large expressions from being compiled or to manage their complexity, here are a few strategies you can consider:

1. Expression Length Limit

You can impose a limit on the length of the expression string before attempting to compile it. This is a simple way to ensure that extremely large expressions are not compiled.

std::string expr = "some large expression...";

// Set a maximum length for the expression

size_t max_length = 1000; // Adjust according to your needs

if (expr.length() > max_length) {

std::cerr \<\< "Expression too large to compile" \<\< std::endl;

return;

}