Question

How to set a buffer size to 2 terabytes in C++

Answer 1

// A terabyte is:
// 1 TB = 1,099,511,627,776 bytes (binary, 2⁴⁰)
// 1 TB = 1,000,000,000,000 bytes (decimal, SI)

// Using constexpr

#include <iostream>
#include <locale>
#include <format>

int main() {
    // Define a terabyte constant (1 TiB = 2^40 bytes)
    constexpr std::size_t TERABYTE = 1ULL << 40;

    // Set buffer size to 2 TB
    std::size_t buffer_size = 2 * TERABYTE;

    // 1. Standard Output (No commas)
    std::cout << "buffer_size (no commas):   "
              << buffer_size << " bytes\n";

    try {
        // 2. Imbue locale for comma formatting
        std::cout.imbue(std::locale("en_US.UTF-8"));

        std::cout << "buffer_size (with imbue):  "
                  << buffer_size << " bytes\n";

        // 3. std::format using the same locale
        std::cout << "buffer_size (with format): "
                  << std::format(std::locale("en_US.UTF-8"),
                                 "{:L}", buffer_size)
                  << " bytes\n";

    } catch (const std::runtime_error& e) {
        std::cerr << "Locale not supported: " << e.what() << '\n';
    }
}


/* 
run:

buffer_size (no commas):   2199023255552 bytes
buffer_size (with imbue):  2,199,023,255,552 bytes
buffer_size (with format): 2,199,023,255,552 bytes

*/

 

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