Z3打印评价结果

Question

In Z3, how can we write a program to get the result from evaluation? By default model.eval(expression) will return another expression of the evaluation result. How can I assign the result to a type-specific data? Below is what I want to do in my program.

int a = model.eval(x + 1)  // compiler error

Answer 1

Sometimes models are not complete. For instance, when nothing depends on the value of x , then Z3 may not assign any value at all to it, ie, you're free to chose whatever value suits you. The eval function has a second argument, which, when set to true , will enable model completion, ie, eval will substitute those don't-cares with some legal value (often 0).

Z3-ints are actual integers, not C/C++-ints smaller than 2^32-1, so the conversion is not performed automatically. If you know that in your application this will always be ok, and that eval will always return a numeral, then you can use Z3_get_numeral_int to perform that conversion.