14.2.8 Integer Conversions

This section describes the options for the %d, %i, %o, %u, %x, and %X conversion specifications. These conversions print integers in various formats.

The %d and %i conversion specifications both print an numeric argument as a signed decimal number; while %o, %u, and %x print the argument as an unsigned octal, decimal, or hexadecimal number (respectively). The %X conversion specification is just like %x except that it uses the characters ABCDEF as digits instead of abcdef.

The following flags are meaningful:

-

Left-justify the result in the field (instead of the normal right-justification).

+

For the signed %d and %i conversions, print a plus sign if the value is positive.

For the signed %d and %i conversions, if the result doesn't start with a plus or minus sign, prefix it with a space character instead. Since the + flag ensures that the result includes a sign, this flag is ignored if you supply both of them.

#

For the %o conversion, this forces the leading digit to be 0, as if by increasing the precision. For %x or %X, this prefixes a leading 0x or 0X (respectively) to the result. This doesn't do anything useful for the %d, %i, or %u conversions.

0

Pad the field with zeros instead of spaces. The zeros are placed after any indication of sign or base. This flag is ignored if the - flag is also specified, or if a precision is specified.

If a precision is supplied, it specifies the minimum number of digits to appear; leading zeros are produced if necessary. If you don't specify a precision, the number is printed with as many digits as it needs. If you convert a value of zero with an explicit precision of zero, then no characters at all are produced.