Müsste in jedem Programmierhandbuch für C zu finden sein: itoa()
char* itoa (int __val, char * __s, int __radix)
Convert an integer to a string.
The function itoa() converts the integer value from val into an ASCII
representation that will be stored under s. The caller is responsible
for providing sufficient storage in s.
The minimal size of the buffer s depends on the choice of radix. For
example, if the radix is 2 (binary), you need to supply a buffer with a
minimal length of 8 * sizeof (int) + 1 characters, i.e. one character
for each bit plus one for the string terminator. Using a larger radix
will require a smaller minimal buffer size.
If the buffer is too small, you risk a buffer overflow. Conversion is
done using the radix as base, which may be a number between 2 (binary
conversion) and up to 36. If radix is greater than 10, the next digit
’9’ will be the letter ’a’.
If radix is 10 and val is negative, a minus sign will be prepended. The
itoa() function returns the pointer passed as s.