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Printf: format whole floats as integers #12

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Printf: format whole floats as integers #12

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Printf: format whole floats as integers
gsurkov Oct 29, 2025
8202e16
Merge remote-tracking branch 'origin/bsb' into gsurkov/printf_whole_long
gsurkov Nov 28, 2025
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12 changes: 12 additions & 0 deletions lib/print/printf_tiny.c
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,11 @@
#include <float.h>
#endif

#if defined(PRINTF_SUPPORT_LONG_LONG) && defined(PRINTF_SUPPORT_EXPONENTIAL)
#include <math.h>
#include <limits.h>
#endif

// output function type
typedef void (*out_fct_type)(char character, void* buffer, size_t idx, size_t maxlen);

Expand Down Expand Up @@ -523,6 +528,13 @@ static size_t _etoa(
prec = PRINTF_DEFAULT_FLOAT_PRECISION;
}

// if value is a whole number, print it using %ll method
#if defined(PRINTF_SUPPORT_LONG_LONG)
if(flags & FLAGS_ADAPT_EXP && value < nextafter(ULONG_LONG_MAX, 1) && value == floor(value)) {
return _ntoa_long_long(out, buffer, idx, maxlen, value, negative, 10, 0, width, flags);
}
#endif

// determine the decimal exponent
// based on the algorithm by David Gay (https://www.ampl.com/netlib/fp/dtoa.c)
union {
Expand Down