Unary ++ operator in Delphi

Question

I suspect the answer is no, but is there any equivalent to the C++ unary pre and postfix incremement operator "++". For example.

int test = 1;
SomeFunc(test++);    // test is 1 inside SomeFunc and 2 afterwards
test = 1;
Somefunc(++test);    // test is 2 inside SomeFunc and 2 afterwards

I know about the Inc (and Dec) operator in Delphi, but you can't pass it to a function as in:

test: Integer;
//...
SomeFunc(Inc(test));   // compiler error, incompatible types

In addition to the compilation error, there does not appear to be a different pre and postfix increment. Its not a big problem writing code like this:

SomeFunc(test);
test := (test + 1);
SomeFunc(test);

but the ++ (and --) operators in C++ are a great feature.

Answer 1

There is no equivalent functionality built in to Delphi.

You might contemplate writing functions like this:

function PostInc(var Value: Integer): Integer;
begin
  Result := Value;
  inc(Value);
end;

function PreInc(var Value: Integer): Integer;
begin
  inc(Value);
  Result := Value;
end;

You would probably wish to make any such functions inline. Although it is open to debate as to how useful such functions would be.

---

Personally I feel that these operators are sometimes convenient in C and C++, but the case for them is not overwhelming. Certainly for beginners, they present a huge trap to fall in to as can be seen by the steady stream of questions here asking about expressions like ++i++ + i++.

FWIW, your description of the operators is imprecise. You said:

int test = 1;
SomeFunc(test++);    // test is 1 inside SomeFunc and 2 afterwards

That is not correct. The variable test is incremented before SomeFunc is called, because a function call is a sequence point. So, test has value 2 if observed from inside SomeFunc. But the value passed to SomeFunc is 1. This program:

#include <iostream>

int test = 1;

void foo(int x)
{
    std::cout << x << std::endl;
    std::cout << test << std::endl;
}

int main()
{
    foo(test++);
}

outputs

1
2