Format String Syntax

All characters except format specifiers are copied unchanged into the resulting string. The standard character to start a format specifier is the % character (percent sign), To display the % sign itself, its doubling %% is used.

Format specifier structure

The format specifier is:

%[flags][width][.accuracy]type

The required components are the start character of the specifier format (%) and type.

Flags

Sign	Name of the sign	Value	In the absence of this sign	Note
`-`	minus	the output value is left aligned within minimum field width	by right
`+`	plus	always indicate the sign (plus or minus) for the decimal output numerical value	only for negative numbers
	space	place a space before the result if the first character of the value not a sign	output can start with a number	The + character has higher priority than the space character. ISPOLAIS for decimal numeric results only.
`#`	octothorpe	"alternative form" of outputting the value		when displaying numbers in the format, a special feature will be indicated before the number format (see below).
`0`	zero	pad the field to the width specified in the `width` field escape sequence, symbol `0`	pad with spaces	if the minus '-' flag is specified, this flag is also ignoredя.

Width

Width(decimal) specifies the minimum field width (including sign for numbers). If the value representation is larger than the field width, then the entry goes outside the field (for example, %2i for the value 100 will give a field value of three characters) if the value representation is less than specified number, it will be padded (by default) with spaces on the left, behavior can be modified by preceding flags. If this method is specified negative width modifier, it is considered that the - flag is set, and the width modifier value is set to absolute.

Accuracy

indicates the minimum number of characters that must appear after the decimal point (dot) when processing types a, A, e, E, f, F;
maximum number of significant characters for types g and G.

The precision is specified as a point followed by a decimal number if number is missing (only a dot is present), then it is assumed that the number is zero. The dot is used to indicate precision even in case when a comma is output when outputting floating point numbers.

Type

The type indicates a specific representation of the output value. Recorded as one character. Unlike other fields, it is required.

Values of type:

f and F are floating point numbers. Default are displayed with a precision of 6 if the modulo number is less than one, before the decimal point is written 0. Values ±∞ are represented in the form [-]inf or [-]infinity (depending on the platform); Nan value is represented as [-]nan or [-]nan(any text below). Using F prints the specified values in capital letters ([-]INF, [-]INFINITY, NAN). In "alternative form" the decimal point character is written even if it is not followed by numbers.
e and E —floating-point numbers in scientific notation recording form (type 1.1e+44). e displays the "e" character at the bottom case, E —in uppercase (3.14E+0);
g and G are floating point numbers. Form representation depends on the value of the quantity (f or e, for G - F or E). Let the variable P equal to precision if the precision specified is not zero, 6 - if precision is not specified, or 1 - if equal to 0. Let X is the exponent of a number in scientific notation. Then, if P > X ≥ −4, then the representation type will be f (F), and precision is P − 1 − X, otherwise type is e (E), accuracy - P − 1. If "alternative" is not selected form", then the leading zeros to the right of the decimal point symbol are not displayed, and the dot part is not displayed if the number is an integer.
a and A —floating point number in hexadecimal form.