How to get the value of a Clang variable initialization

clang_get_init_value_of_expr.cpp

// clang::VarDecl * varDecl;
// clang::ASTContext & ctx;

const clang::Expr * initializerExpr = varDecl->getInit();

llvm::APSInt result;
if (initializerExpr->EvaluateAsInt(result, ctx)) {
    std::cout << "Value as string: " << result.toString(10) << std::endl;
}