std::basic_ostream::tellp(3)

💅 std::basic_ostream::tellp — C++ Standard Library, but make it make sense

okay so bestie, welcome to std::basic_ostream::tellp(3) from the C++ Standard Library — yes that's the whole manual name, we're being official today 🎀. This one's a little function with big main character energy: it tells you where you are in your output stream. That's it. That's the vibe. Let's get into it ✨

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📛 NAME

std::basic_ostream::tellp — literally std::basic_ostream::tellp, no notes, the name ate 💅

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🌸 Synopsis

pos_type tellp();

So what does it actually do? It returns the output position indicator of the current associated streambuf object. Think of it as the little cursor bookmark of your output stream — where's the next character gonna land? This function knows 🔥

It behaves as an UnformattedOutputFunction (except without actually performing output) — and heads up, that "(since C++11)" applies to that no-actual-output part. After constructing and checking the sentry object:

• If fail()==true, it returns pos_type(-1).
• Otherwise, it returns rdbuf()->pubseekoff(0, std::ios_base::cur, std::ios_base::out).

Yes the whole call is that long, no we're not abbreviating it, character for character bestie 🫶

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🙈 Parameters

• (none) — she takes nothing, she gives everything. Periodt.

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💖 Return value

• current output position indicator on success ✅
• pos_type(-1) if a failure occurs 💀

That's the whole deal. Success = a real position, failure = that sad little -1.

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🦋 Example

the original page has one of those // Run this code buttons, and here's the code it runs:

#include <iostream>
#include <sstream>
int main()
{
    std::ostringstream s;
    std::cout << s.tellp() << '\n';
    s << 'h';
    std::cout << s.tellp() << '\n';
    s << "ello, world ";
    std::cout << s.tellp() << '\n';
    s << 3.14 << '\n';
    std::cout << s.tellp() << '\n' << s.str();
}

🍓 Output

0
1
13
18
hello, world 3.14

and honestly? watching the position tick up 0 → 1 → 13 → 18 while the string quietly builds itself into hello, world 3.14 is lowkey iconic 🌈

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👑 See also

• seekp — sets the output position indicator (public member function)
• tellg — returns the input position indicator (public member function of std::basic_istream<CharT,Traits>)
• seekg — sets the input position indicator (public member function of std::basic_istream<CharT,Traits>)

like tellp's whole friend group fr fr 💜

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aaaand that's the page! source is http://cppreference.com, version 2024.06.10, and this gorgeous little entry is std::basic_ostream::tellp(3) — go check your stream position bestie, ily, bye 💅✨🎀