ToString() creates an object on the heap?

Question

num.ToString() Will create an object on the heap during the execution of WriteLine()?

int num = 83424;
Console.WriteLine(num.ToString());

Answer 1

Almost certainly, yes. There may be some behind-the-scenes tricks to avoid allocations for some small integers, zero, etc (a quick test in .NET 6 and .NET 7 suggests this is the case for 0-9 inclusive).

If that isn't desirable, there are ways of avoiding it - for example Utf8Formatter has methods to write primitives to a span, typically some reusable buffer memory - but this has a different API and usage than ToString().