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Inconsistent Output When Using `sprintf` with Floating-Point Precision in C

👀 Views: 47 đŸ’Ŧ Answers: 1 📅 Created: 2025-06-07
c sprintf floating-point C

I'm trying to implement I'm attempting to set up I've been banging my head against this for hours... I'm working with an scenario with formatting floating-point numbers using `sprintf` in C. I'm trying to format a double to a specific precision, but the output seems inconsistent across different values. For example, when I run the following code: ```c #include <stdio.h> int main() { double num1 = 12345.6789; double num2 = 0.00012345; char buffer[50]; sprintf(buffer, "%.4f", num1); printf("Formatted num1: %s\n", buffer); sprintf(buffer, "%.4f", num2); printf("Formatted num2: %s\n", buffer); return 0; } ``` I expect `num1` to be printed as `12345.6789` and `num2` as `0.0001`, but instead, I see: ``` Formatted num1: 12345.6789 Formatted num2: 0.0001 ``` This is the output I expect for `num1`, but I find it odd that `num2` gets rounded to `0.0001` instead of showing more important digits or even `0.00012`. I also tried using `%.6f` and `%.8f` but the behavior remains the same. Is there something I'm missing about how `sprintf` handles precision with very small numbers? I'm compiling with GCC version 11.1.0 under Linux. Any insights into this behavior would be greatly appreciated! For context: I'm using C on Linux. Has anyone dealt with something similar? This is happening in both development and production on Debian. I'm working with C in a Docker container on Linux. Thanks in advance!