How Can We Precisely Format Floating-Point Numbers to Eliminate Unnecessary Zeros?

Precision Formatting of Floating-Point Numbers: Eliminating Unnecessary Zeros

When representing numerical data, it can be challenging to balance precision and readability, especially when dealing with floating-point numbers. The issue arises when printing these numbers, which often results in trailing zeros or unnecessary decimal places.

Problem:

Consider using double type to represent all numerical values, including integers. However, printing these pseudo-integers as doubles results in the problem of trailing zeros for small values.

Desired Output:

The goal is to print doubles in a clean format, suppressing trailing zeros for integer values while maintaining precision for actual doubles.

Solution:

To effectively handle this situation, a custom formatting function can be implemented that leverages the fact that double can precisely represent integers up to 2⁵³. The function, named fmt(double d), works as follows:

if (d == (long) d) {
    return String.format("%d", (long) d);
} else {
    return String.format("%s", d);
}

This allows for printing pseudo-integers as integers by utilizing the %d format specifier, while actual doubles retain their precision using the %s specifier.

Example Output:

The custom formatting function produces the following output:

232
0.18
1237875192
4.58
0
1.2345

Performance Optimization:

By avoiding string manipulation, the fmt function ensures efficient performance. In contrast, solutions relying on trimming zeros would incur a significant performance penalty due to string operations.

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