Converting float to char*

Question

How can I convert a float value to char* in C language?

Answer 1

Long after accept answer.

Use sprintf(), or related functions, as many others have answers suggested, but use a better format specifier.

Using "%.*e", code solves various issues:

• The maximum buffer size needed is far more reasonable, like 18 for float (see below). With "%f", sprintf(buf, "%f", FLT_MAX); could need 47+. sprintf(buf, "%f", DBL_MAX); may need 317+

• Using ".*" allows code to define the number of decimal places needed to distinguish a string version of float x and it next highest float. For deatils, see Printf width specifier to maintain precision of floating-point value

• Using "%e" allows code to distinguish small floats from each other rather than all printing "0.000000" which is the result when |x| < 0.0000005.

Example usage

#include 
#define FLT_STRING_SIZE (1+1+1+(FLT_DECIMAL_DIG-1)+1+1+ 4   +1)
                     //  - d .  ffffdffffffffd           e - ffffdd \0

char buf[FLT_STRING_SIZE];
sprintf(buf, "%.*e", FLT_DECIMAL_DIG-1, some_float);

Ideas:
IMO, better to use 2x buffer size for scratch pads like buf[FLT_STRING_SIZE*2].
For added robustness, use snprintf().

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As a 2nd alterative consider "%.*g". It is like "%f" for values exponentially near 1.0 and like "%e" for others.