How Can I Convert a Double to a String with Precise Decimal Places Without Rounding?

Formatting Double to String with Precision: A Truncated Approach

The task of converting a Double to a String with a specific number of decimal places, without rounding, can be achieved through a tailored approach.

The crux of the solution lies in utilizing the Math.Truncate() method. This method effectively truncates any decimal places, discarding all values after a specified point. By strategically multiplying the Double by a power of ten, you can easily isolate the desired number of decimal places.

For instance, to limit a Double to two decimal places, follow this formula:

double x = Math.Truncate(myDoubleValue * 100) / 100;

Consider a value of 50.947563. Applying the formula, we obtain the following:

x = Math.Truncate(50.947563 * 100) / 100
x = Math.Truncate(5094.7563) / 100
x = 50.94

With the truncated value at hand, you can effortlessly format it as a string using string.Format() with the "N2" format specifier. This format ensures the preservation of the exact decimal places without rounding, while also respecting culture-specific number formatting.

For example:

string s = string.Format("{0:N2}%", x);

This code generates the string "50.94%", where the percentage symbol reflects the specific format requested.

By employing the Math.Truncate() method and a precise format string, you can effectively convert a Double to a String, eliminating any undesired rounding and preserving the original value with the desired precision.

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