Python built-in type (4) -- value, python built-in

Python built-in type (4) -- value, python built-in

 
Python has three numeric types: integer, floating point numbers, and plural ). In addition, Boolean is the subtype of an integer.

Value Type description

An integer is represented by 1-N numeric characters. The integer type name isintAll integers are of the type.intThe floating point is composed of an integer and a decimal part..Connection. The floating point type name isfloatAll floating point numbers are of the type.floatThe complex number consists of the real part and the virtual part, where the virtual part follows the letterj, The number of plural type namescomplex, All plural values are typescomplex.

Value declaration

In python, there are two ways to declare a value: literal declaration and numerical constructor initialization.

Literal

Similar to other languages, python supports literal value declaration.

For integers, a string of numbers indicates a positive integer, and a negative number is added before the number.-Number,

# Positive number >>>> 19 19 # negative number >>>>-7-7 #0 >>> 00

The literal value of the floating point number. The negative value is also the one added above.-Number,

# Positive floating point number> 19.119.1 # negative floating point number>-7.2-7.2 #0.0 >>> 0.00.0

The literal expression of the plural. The imaginary part uses letters.j(OrJ) Indicates

>>> 1 + 2j1 + 2j

Integers are represented in decimal notation by default, but the literal value can also be directly declared in binary notation, octal notation, or hexadecimal notation. They are added to integers respectively.0b,0o,0x.

#2 hexadecimal >>> a = 0b10 >>> a2 #8 hexadecimal >>> B = 0o10 >>> b8 #16 hexadecimal >>> c = 0x10 >>> c16

Constructor Declaration

intA function is a python built-in function and also an integer type.intIt initializes the input parameters and converts them to an integer. The initialization results vary according to the input parameters. For details, see Python built-in function 33 -- int.

#1. if no parameter is input, the result 0 >>> int () 0 #2 is displayed. when an integer is input, the return value is itself. When a floating point number is input, the value is rounded down to >>>> int (3) 3 >>> int (3.6) 3 #3. when a string is input, it is converted to 10 by default. The string can contain positive and negative symbols. >>> Int ('+ 36') 36 >>> int ('-36 ')-36 #4. Specify the conversion hexadecimal format when passing in the string. >>> Int ('01', 2) 1 >>> int ('02 ', 3) 2 >>> int ('07', 8) 7 >>> int ('0f', 16) 15

floatA function is a python built-in function and also a floating point type.floatIt initializes the input parameters and converts them to a floating point number. The initialization results vary according to the input parameters. For details, see Python built-in function 22 -- float.

#1. if no parameter is input, the result is 0.0 >>> float () 0.0 #2. input an integer or floating point number >>>> float (3) 3.0 >>> float (3.6) 3.6 #3. when a string is input, it can contain positive and negative characters. >>> Float ('+ 000000') 3.6 >>> float ('-000000')-3.6 #4. several special strings> float ('infinity ') # Infinity inf> float ('inf') # inFinIty inf> float ('infinity ') # case insensitive inf >>> float ('+ inFinIty') # positive inFinIty inf >>> float ('-inFinIty ') # negative infinity-inf> float ('nan ') # No nan Value

complexA function is a python built-in function and also a complex number.complexThe constructor is used to initialize the input parameters and convert them into a plural number. The initialization results vary according to the input parameters. For details, see Python built-in function 13 -- complex.

#1. if no parameter is input, the result is 0j >>> complex () 0j #2. two parameters are passed in, indicating the real part and the virtual part >>> complex (3, 4) (3 + 4j) #3. when passing in a string >>> complex ('3 + 4j ') 3.6 >>> complex ('-100') (3 + 4j)

Supported operation Operations common operation operations

Shaping supports the following operations, sorted in ascending order of priority

• x + yAdd
• x - ySubtraction
• x * yMultiply
• x / yDivision
• x // yFloor Division
• x % yReturns the remainder.
• -xTake negative
• +xPositive value, value unchanged
• abs(x)Take absolute value
• int(x)Convert to integer
• float(x)Convert to floating point
• complex(re,im)Convert to plural
• c.conjugate()Take the combination of the plural
• divmod(x， y)Returns the result of the floor division and the result of the remainder.
• pow(x,y)Y Power of x
• x ** yY Power of x

Wherex // yOnly floating-point numbers and integers are supported, and plural numbers are not supported. The division result is rounded down.

>>> 1 // 20 >>>-1 // 2-1 >>>> 1 // (-2)-1 >>>> (-1) // (-2) 0 # One of the floating point results is also a floating point >>>> 5 // 31 >>> 5 // 3.01.0

Rounding a floating point

Python provides the built-in function float for rounding floating point numbers. Note that if float does not input 1.1 parameters, it is truncated to an integer. It is different from entering 0 to retain 0 decimal places.

>>> Round (3.456, 2) 3.46 >>> round (3.456, 1) 3.5 >>> round (3.456, 0) 3.0 >>> round (3.456) # If no parameter is input, the result is an integer of 3.

Several truncation methods for converting a floating point to an integer

InmathIn the module, there are several other methods to truncate floating point numbers into decimal places. They aretruncTruncation,floorRound down,ceilRounded up. As mentioned aboveroundFunction. If no 2nd parameters are input, the function can also be rounded up.

# Import mathimport math >>>> a = 3.556 >>> B =-3.556 # directly truncation >>> math. trunc (a) 3> math. trunc (B)-3 # Round down> math. floor (a) 3 >>> math. floor (B)-4 # rounded up> math. ceil (a) 4> math. ceil (B)-3 # rounding to integer> round (a) 4 >>> round (B)-4

Floating Point is_integer()Method

is_integer()Is an instance method of floating number,
If the floating point instance is an integer, returnTrueOtherwise, returnFalse.

>>> f1 = 3.0>>> f1.is_integer()True>>> f2 = 3.14>>> f2.is_integer()False