mirror of
https://github.com/DaveGamble/cJSON.git
synced 2023-08-10 21:13:26 +03:00
cJSON: Fix print_number to print significant digits of doubles
This commit is contained in:
56
cJSON.c
56
cJSON.c
@ -410,27 +410,6 @@ static void update_offset(printbuffer * const buffer)
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buffer->offset += strlen((const char*)buffer_pointer);
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}
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/* Removes trailing zeroes from the end of a printed number */
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static int trim_trailing_zeroes(const unsigned char * const number, int length, const unsigned char decimal_point)
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{
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if ((number == NULL) || (length <= 0))
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{
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return -1;
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}
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while ((length > 0) && (number[length - 1] == '0'))
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{
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length--;
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}
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if ((length > 0) && (number[length - 1] == decimal_point))
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{
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/* remove trailing decimal_point */
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length--;
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}
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return length;
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}
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/* Render the number nicely from the given item into a string. */
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static cJSON_bool print_number(const cJSON * const item, printbuffer * const output_buffer, const internal_hooks * const hooks)
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{
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@ -438,9 +417,9 @@ static cJSON_bool print_number(const cJSON * const item, printbuffer * const out
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double d = item->valuedouble;
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int length = 0;
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size_t i = 0;
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cJSON_bool trim_zeroes = true; /* should zeroes at the end be removed? */
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unsigned char number_buffer[64]; /* temporary buffer to print the number into */
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unsigned char number_buffer[26]; /* temporary buffer to print the number into */
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unsigned char decimal_point = get_decimal_point();
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double test;
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if (output_buffer == NULL)
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{
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@ -452,20 +431,22 @@ static cJSON_bool print_number(const cJSON * const item, printbuffer * const out
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{
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length = sprintf((char*)number_buffer, "null");
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}
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else if ((fabs(floor(d) - d) <= DBL_EPSILON) && (fabs(d) < 1.0e60))
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/* This checks for negative zero */
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else if (d == 0)
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{
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/* integer */
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length = sprintf((char*)number_buffer, "%.0f", d);
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trim_zeroes = false; /* don't remove zeroes for "big integers" */
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}
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else if ((fabs(d) < 1.0e-6) || (fabs(d) > 1.0e9))
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{
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length = sprintf((char*)number_buffer, "%e", d);
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trim_zeroes = false; /* don't remove zeroes in engineering notation */
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length = sprintf((char*)number_buffer, "0");
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}
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else
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{
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length = sprintf((char*)number_buffer, "%f", d);
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/* Try 15 decimal places of precision to avoid nonsignificant nonzero digits */
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length = sprintf((char*)number_buffer, "%1.15g", d);
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/* Check whether the original double can be recovered */
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if ((sscanf((char*)number_buffer, "%lg", &test) != 1) || ((double)test != d))
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{
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/* If not, print with 17 decimal places of precision */
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length = sprintf((char*)number_buffer, "%1.17g", d);
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}
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}
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/* sprintf failed or buffer overrun occured */
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@ -474,15 +455,6 @@ static cJSON_bool print_number(const cJSON * const item, printbuffer * const out
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return false;
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}
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if (trim_zeroes)
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{
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length = trim_trailing_zeroes(number_buffer, length, decimal_point);
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if (length <= 0)
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{
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return false;
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}
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}
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/* reserve appropriate space in the output */
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output_pointer = ensure(output_buffer, (size_t)length, hooks);
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if (output_pointer == NULL)
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