std::showba...::noshowbase(3)

💖 NAME 💖

okay so bestie, this is the std::showba...::noshowbase(3) page from the C++ Standard Libary (yes, that’s how the header spells it, and we respect the icon behavior 💅). The stars of the show are std::showbase and std::noshowbase.

std::showbase,std::noshowbase — std::showbase,std::noshowbase. The original NAME line literally says std::showbase,std::noshowbase - std::showbase,std::noshowbase, and we are keeping it exactly, no notes, iconic.

✨ Synopsis ✨

          Defined in header <ios>
          std::ios_base& showbase( std::ios_base& str );   (1)
          std::ios_base& noshowbase( std::ios_base& str ); (2)

1. Enables the showbase flag in the stream str as if by calling str.setf(std::ios_base::showbase).
2. Disables the showbase flag in the stream str as if by calling str.unsetf(std::ios_base::showbase).

This is an I/O manipulator, so it may be called with an expression such as out << std::showbase for any out of type std::basic_ostream, or with an expression such as in >> std::showbase for any in of type std::basic_istream. 🫶

The showbase flag affects the behavior of integer output (see std::num_put::put), monetary input (see std::money_get::get) and monetary output (see std::money_put::put). It’s giving “one flag, multiple departments,” honestly.

🎀 Parameters 🎀

• str — reference to I/O stream 😌

💫 Return value 💫

str — reference to the stream after manipulation. She comes back changed, but still herself. 💖

🌸 Notes 🌸

As spelled out in std::num_put::put, the showbase flag in integer output acts like the # format specifier in std::printf, which means the numeric base prefix is not added when outputting the value zero. That’s the whole note, bestie — zero does not get the lil prefix, no cap. 💀

🧚 Example 🧚

// Run this code

        #include <iomanip>
        #include <iostream>
        #include <locale>
        #include <sstream>

        int main()
        {
            // showbase affects the output of octals and hexadecimals
            std::cout << std::hex
                      << "showbase: " << std::showbase << 42 << '\n'
                      << "noshowbase: " << std::noshowbase << 42 << '\n';

            // and both input and output of monetary values
            std::locale::global(std::locale("en_US.utf8"));
            long double val = 0;
            std::istringstream is("3.14");
            is >> std::showbase >> std::get_money(val);
            std::cout << "With showbase, parsing 3.14 as money gives " << val
       << '\n';
            is.seekg(0);
            is >> std::noshowbase >> std::get_money(val);
            std::cout << "Without showbase, parsing 3.14 as money gives " <<
       val << '\n';
        }

🌈 Output 🌈

        showbase: 0x2a
        noshowbase: 2a
        With showbase, parsing 3.14 as money gives 0
        Without showbase, parsing 3.14 as money gives 314

🔥 See also 🔥

• resetiosflags — clears the specified ios_base flags (function).
• setiosflags — sets the specified ios_base flags (function).

mwah 💋 source/version sign-off: http://cppreference.com, 2024.06.10, page std::showba...::noshowbase(3). byeee, go show or noshow that base bestie 🫶✨