Python getting started note (6): About the Value Type

I. Standard Functions

Cmp (): Compare the size

Str (): Convert to string

Type (): type

Cmp (...) cmp (x, y)-> integer Return negative (negative) if x <y, zero (0) if x = y, positive (positive) if x> y.

As follows:

>>> cmp(5,3.2)1>>> cmp(3.5,8)-1

Ii. Conversion factory Functions

Loss of Precision

>>> int(1.847)1>>> long(42)42L>>> float(42)42.0>>> complex(42)(42+0j)>>> complex(2.4,-8)(2.3999999999999999-8j)

Iii. Functions

Used for numerical calculation: asb (), coerce (), divmod (), pow (), round ()

Asb (): absolute; complete; authoritarian; n: absolute

>>> abs(-1)1

Coerce (): vt. Force, force,
Type conversion, but provides custom two numeric types instead of relying on the python interpreter. A parent is returned, and a forced action exists.
Coerce (...)
Coerce (x, y)-> (x1, y1)

Return a tuple consisting of the two numeric arguments converted
A common type, using the same rules as used by arithmetic operations.
If coercion is not possible, raise TypeError.

>>> coerce(1,2)(1, 2)>>> coerce(1.2,2l)(1.2, 2.0)>>> coerce(1.2,2)(1.2, 2.0)>>> coerce(1,2.3)(1.0, 2.2999999999999998)>>> coerce(1j,123)(1j, (123+0j))

Divmod ():. divmod division remainder, returns the ancestor containing the quotient and remainder

>>> divmod(10,3)(3, 1)>>> divmod(3,10)(0, 3)>>> divmod(10,2.5)(4.0, 0.0)

Pow (): power of a number: exponential meaning

Both pow () and ** can implement exponential operations. pow () is born first.

>>> pow(2,5)32>>> 2**532

Round (): Rounding

Round (...)
Round (number [, ndigits])-> floating point number

Round a number to a given precision in decimal digits (default 0 digits ).
This always returns a floating point number. Precision may be negative.

>>> round(1.234,2)1.23>>> round(3.14)3.0>>> for each in range(10):     print round(math.pi,each)3.03.13.143.1423.14163.141593.1415933.14159273.141592653.141592654

4. Only integer Functions

Oct (): octonary number system octal string format

>>> oct(255)'0377'

Hex (): hexadecimal number system hexadecimal string format

>>> hex(255)'0xff'

ASCII Code Conversion Function

Ord (): ordinal number, which converts a character to an integer.

>>> ord('A')65

Chr (): char: a single character. The number pair should be ASCII characters.

>>> chr(65)'A'

5. Operators

>>> X> = 80 and x <= 100 True> 80 <= x <= 100True ----------------------------- always writes an error: >>> 80 = <x <= 100 SyntaxError: invalid syntax

Vi. Usage

1. Score level

def result(x):   dic={9:'A',8:'B',7:'C',6:'D'}   myre=x/10   for obj in sorted(dic.keys(),reverse=True):       if myre>= obj:           out=dic[obj]           break       else:           out='F'   return outif __name__=="__main__":    sorce = input('Enter your sorce:')    print 'level:%s' %result(sorce)