to_string-floating-type

• C++ function to convert floating type to string to_string<T>

void test1(void)
{
    float  f = 10.12f;
    double d = 10.12;

    std::cout << std::fixed
              << f    // 10.120000
              << " "
              << d    // 10.120000
              << std::endl;
    
    std::cout << std::fixed
              << j2::to_string<float>(f)  // 10.119999886 
              << " "
              << j2::to_string<double>(d) // 10.11999999999999922 
              << std::endl;
    
    std::cout << std::fixed
              << j2::to_string<float>(f, 2)  // 10.12
              << " "
              << j2::to_string<double>(d, 2) // 10.12
              << std::endl;
    
    std::cout << std::fixed
              << j2::to_string<float>(f,10)  // 10.1199998856 
              << " "
              << j2::to_string<double>(d,20) // 10.11999999999999921840
              << std::endl;
}

• C++ function to compare floating type to string is_equal<T>

void test_double(double d1, double d2, long long precision)
{
    bool ret = j2::is_equal<double>(d1, d2, precision);

    if (ret) { std::cout << "[equal] "; } else { std::cout << "[not equal] "; }

    std::cout << std::fixed
              << j2::to_string<double>(d1, precision) << " " << j2::to_string<double>(d2, precision)
              << std::endl;
}

void test2()
{
    test_double(10.12, 10.12,       2); // [equal]     10.12  10.12
    test_double(10.12, 10.1,        1); // [equal]     10.1   10.1
    test_double(10.12, 10.12,       3); // [equal]     10.120 10.120
    test_double(10.12, 10.121,      3); // [not equal] 10.120 10.121
    test_double(10.12, 10.121,     20); // [not equal] 10.11999999999999921840 10.12100000000000044054
    test_double(10.12, 10.1201,    20); // [not equal] 10.11999999999999921840 10.12010000000000076170
    test_double(10.12, 10.12001,   20); // [not equal] 10.11999999999999921840 10.12001000000000061618
    test_double(10.12, 10.120001,  20); // [not equal] 10.11999999999999921840 10.12000100000000024636
    test_double(10.12, 10.1200001, 20); // [not equal] 10.11999999999999921840 10.12000010000000038701
    test_double(10.12, 10.12,      10); // [equal] 10.1200000000 10.1200000000
}

License

• to_string-floating-type is under MIT License. https://github.com/j2doll/to_string-floating-type
• It is a part of JayTwo(j2) Library.

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