Format Modifiers

A format modifier alters or extends the format specification, allowing more specialized output. The format modifiers may be in any order and are all optional.

Flags (in any order)

Flag	Operation
'-'	left-justify the output in the field
'+'	always print a sign ('+' or '-') for numeric types
' '	if a number's sign is not printed then print a space in the sign position
'0'	pad numeric output with zeros not spaces

• If both the '+' and ' ' flags are used in the same format specification then the ' ' flag is ignored.
• If both the '-' and '0' flags are used in the same format specification then the '-' flag is ignored.

Alternate output:

• For the octal format code add a leading zero.
• For the hexadecimal format code add a leading '0x'.
• For floating point format codes the output will always have a radix character.

Field Width

<w>where <w> is a number specifying a minimum field width. The converted argument will be printed in a field at least this wide, and wider if necessary. If the converted argument takes up fewer display positions than the field width, it will be padded on the left (or right for left justification) to make up the field width. The padding character is normally a space, but it is a zero if the zero padding flag was specified. The special character '*' may be used in place of <w> and indicates the current argument is to be used for the field width value, the actual field or precision follows as the next sequential argument.

Precision

.<p> specifies a period followed by the number <p>, specifying the maximum number of display positions to print from a string, or digits after the radix point for a decimal number, or the minimum number of digits to print for an integer type (leading zeroes will be added to make up the difference). The special character '*' may be used in place of <p> indicating the current argument contains the precision value.

Argument Index

(<n>) where <n> is an integer index into the argument list with the first argument being 1. If no argument index is specified in a format specification the first argument is selected. The next time no argument index is specified in a format specification the second argument is selected and so on. Format specifications with and without argument indexes can be in any order and are independent of each other in operation.

For example, the format string "%u %(4)u %u %(2)u %u" selects the first, fourth, second, second, and third arguments given to OCIFormatString().