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This section discusses the conversion specifications for floating-point numbers: the ‘%f’, ‘%e’, ‘%E’, ‘%g’, and ‘%G’ conversions.
The ‘%f’ conversion prints its argument in fixed-point notation,
producing output of the form
[-
]ddd.
ddd,
where the number of digits following the decimal point is controlled
by the precision you specify.
The ‘%e’ conversion prints its argument in exponential notation,
producing output of the form
[-
]d.
ddde
[+
|-
]dd.
Again, the number of digits following the decimal point is controlled by
the precision. The exponent always contains at least two digits. The
‘%E’ conversion is similar but the exponent is marked with the letter
‘E’ instead of ‘e’.
The ‘%g’ and ‘%G’ conversions print the argument in the style of ‘%e’ or ‘%E’ (respectively) if the exponent would be less than -4 or greater than or equal to the precision; otherwise they use the ‘%f’ style. Trailing zeros are removed from the fractional portion of the result and a decimal-point character appears only if it is followed by a digit.
The following flags can be used to modify the behavior:
Left-justify the result in the field. Normally the result is right-justified.
Always include a plus or minus sign in the result.
If the result doesn’t start with a plus or minus sign, prefix it with a space instead. Since the ‘+’ flag ensures that the result includes a sign, this flag is ignored if you supply both of them.
Specifies that the result should always include a decimal point, even if no digits follow it. For the ‘%g’ and ‘%G’ conversions, this also forces trailing zeros after the decimal point to be left in place where they would otherwise be removed.
Pad the field with zeros instead of spaces; the zeros are placed after any sign. This flag is ignored if the ‘-’ flag is also specified.
The precision specifies how many digits follow the decimal-point
character for the ‘%f’, ‘%e’, and ‘%E’ conversions. For
these conversions, the default precision is 6
. If the precision
is explicitly 0
, this suppresses the decimal point character
entirely. For the ‘%g’ and ‘%G’ conversions, the precision
specifies how many significant digits to print. Significant digits are
the first digit before the decimal point, and all the digits after it.
If the precision is 0
or not specified for ‘%g’ or
‘%G’, it is treated like a value of 1
. If the value being
printed cannot be expressed precisely in the specified number of digits,
the value is rounded to the nearest number that fits.
Next: Other Output Conversions, Previous: Integer Conversions, Up: C-Style I/O Functions [Contents][Index]