Abseil-equivalent of stringstream

[David Chen]

Hi all,

What is the Abseil-equivalent of stringstream, in particular for appending characters to a string buffer? I thought that absl::StrAppend would be the right solution, but the char constructor for AlphaNum is explicitly deleted.

Thank you in advance for your help.

Best,
David

[Rong Jie]

The class you are looking for is absl::Cord

https://github.com/abseil/abseil-cpp/blob/10ac811f7c3720761c0fa0cd2b3fe92116b89420/absl/strings/cord.h#L147

Best regards,

Rong Jie

[Rong Jie]

 Ah, my mistake, seems that absl::Cord also doesn't support explicitly appending char type.

There is kind of a workaround for both absl::Cord (more recommended) and absl::StrAppend if you just want to avoid malloc.

char raw[2] = {0};

s[0] = 'c';

abs::string_view s(raw);

then either absl::StrAppend(dest, s) or cord.Append(s)

[Mark Barolak]

There is an internal type that does what you're asking for: https://github.com/abseil/abseil-cpp/blob/master/absl/strings/internal/ostringstream.h

There isn't a strong reason for it to be internal, but at the time of release there also wasn't a particularly strong reason for it to be public, so it was kept internal to be conservative.  I can ask a bit about making it public, but I should caution that it's not clear what the outcome of that should be.

Taking a step back: David, would you mind describing the problem you're trying to solve a bit more?  is there a reason why you'd like to avoid std::ostringstream?  Personally, I think I would reach for the standard library type without much second thought, so I'm really interested to learn more about why an Abseil type would be preferable.

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[Andy Getzendanner]

On Thu, Jun 20, 2024 at 1:37 AM David Chen <david....@gmail.com> wrote:

I thought that absl::StrAppend would be the right solution, but the char constructor for AlphaNum is explicitly deleted.

You just need to convert that char to something else before you pass it into StrAppend (or StrCat).

If you want numerals, like "65", do absl::StrAppend(&my_str, static_cast<int>(my_char)).

If you want a single character, like "A", do absl::StrAppend(&my_str, absl::string_view(&my_char, 1)).

These functions reject char arguments because the intent is ambiguous, and we prefer for the code to be unambiguous even though that requires being more explicit in this case.