Format () function in Python

The format () function is built into Python to use to format an input value into a specific format.

Syntax of format () function in Python:

 format(value[, format_spec]) 

Parameters of format function ()

The format () function has 2 parameters:

1. value : value to be formatted.
2. format_spec : the format you want for the value.

Format sets:

Align the result = Set a positive sign (+) or negative (-) in the left margin d Integer format c Unicode character corresponding b Binary format o Definition octal format x Hexadecimal format (lower case) X Hexadecimal format (uppercase) n Decimal format e Hat notation. (lowercase e) E Hat notation. (uppercase E) f Real number floating point format (Default: 6) F Same as 'f', but displays uppercase letters, for example 'inf' is 'INF' and 'nan' is 'NAN' g General format. Round numbers to p significant digits. (Default: 6) G Same as 'g', switch to 'E' if the number is too large. % Percentage.

The order format is as follows:

 [[fill]align][sign][#][0][width][,][.precision][type] 

Inside:

1. fill: is any character
2. align: alignment, "<" | ">" | "=" | "^"
3. sign: sign, "+" | "-" | ""
4. width: string length, is an integer
5. precision: precision, is an integer
6. type: format type, "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"

Value returned from format ()

The format () method returns the formatted result of a given value determined by a specific format.

Example 1: Number format with format ()

 # d, f và b là loại định dạng # số nguyên print(format(123, "d")) # số thập phân # viết bởi TipsMake.com print(format(123.4567898, "f")) # nhị phân print(format(12, "b")) 

Run the program, the result is:

 123 123.456790 1100 

Example 2: Number format with alignment

 # số nguyên print(format(1234, "*>+7,d")) # số thập phân print(format(123.4567, "^-09.3f")) 

Output returns:

 *+1,234 0123.4570 

Here, when formatting the integer 1234, we specify the format including *<+7,d . Why is that? Details are as follows:

1. * Character fill, fill in the blank after formatting.
2. > Right alignment option, so the output string is on the right.
3. + Option to force the output to be signed (with the sign on the left).
4. 7 Optionally specify the length of the result, forcing the return number to have a minimum length of 7 characters, other spaces will be filled with fill characters.
5. , Thousands operators, commas will be placed between thousands of digits and the remaining digits.
6. d option to specify the result is an integer.

When formatting floating point numbers 123.4567, we specify the format including ^-09.3f , details are as follows:

1. ^ option to align the center position, so the output sequence will be in the middle of the specified space.
2. - Option to force the output to display a negative sign.
3. 0 Characters added to the spaces after formatting.
4. 9 Optionally specify the length of the result, forcing the return number to have a minimum length of 9 characters (including decimal points, commas, and a negative sign).
5. .3 precision operator, determine the precision, round to the third digit after the decimal point.
6. f option to specify the result to return is a floating-point number.

Example 3: Use format () by overwriting __format __ ()

 # phương thức __format __ () tùy chỉnh class Person: def __format__(self, format): if(format == 'age'): return '23' return 'None' print(format(Person(), "age")) 

Run the program, the result is:

 23 

Here, we override the __format __ () method of the Person class, and the format () method inside of running Person().__format__("age") to return 23 .

See also: Built-in Python functions