newlib/libc/stdlib/itoa.c

   1 /*
   2 FUNCTION
   3 <<itoa>>---integer to string
   4
   5 INDEX
   6         itoa
   7
   8 SYNOPSIS
   9         #include <stdlib.h>
  10         char *itoa(int <[value]>, char *<[str]>, int <[base]>);
  11         char *__itoa(int <[value]>, char *<[str]>, int <[base]>);
  12
  13 DESCRIPTION
  14 <<itoa>> converts the integer <[value]> to a null-terminated string
  15 using the specified base, which must be between 2 and 36, inclusive.
  16 If <[base]> is 10, <[value]> is treated as signed and the string will be
  17 prefixed with '-' if negative. For all other bases, <[value]> is treated as
  18 unsigned. <[str]> should be an array long enough to contain the converted
  19 value, which in the worst case is sizeof(int)*8+1 bytes.
  20
  21 RETURNS
  22 A pointer to the string, <[str]>, or NULL if <[base]> is invalid.
  23
  24 PORTABILITY
  25 <<itoa>> is non-ANSI.
  26
  27 No supporting OS subroutine calls are required.
  28 */
  29
  30 #include <stdlib.h>
  31
  32 char *
  33 __itoa (int value,
  34         char *str,
  35         int base)
  36 {
  37   unsigned uvalue;
  38   int i = 0;
  39
  40   /* Check base is supported. */
  41   if ((base < 2) || (base > 36))
  42     {
  43       str[0] = '\0';
  44       return NULL;
  45     }
  46
  47   /* Negative numbers are only supported for decimal.
  48    * Cast to unsigned to avoid overflow for maximum negative value.  */
  49   if ((base == 10) && (value < 0))
  50     {
  51       str[i++] = '-';
  52       uvalue = (unsigned)-value;
  53     }
  54   else
  55     uvalue = (unsigned)value;
  56
  57   __utoa (uvalue, &str[i], base);
  58   return str;
  59 }
  60
  61 char *
  62 itoa (int value,
  63         char *str,
  64         int base)
  65 {
  66   return __itoa (value, str, base);
  67 }