Built-in Functions
chr
Converts an integer to a character, the argument must be in the range [0..255]
Raise ValueError
#!/usr/bin/python
for i in xrange(256):
print(chr(i))
complex
Return a complex number
Raise ValueError
c = complex('1+2j') # convert a string to complex
print c, c.real, c.imag
dict
Create a new dictionary
Raise ValueError
a = dict(one=1, two=2, three=3)
c = dict(zip(['one', 'two', 'three'], [1, 2, 3]))
d = dict([('two', 2), ('one', 1), ('three', 3)])
e = dict({'three': 3, 'one': 1, 'two': 2})
eval
Evaluates a string and returns an object
Raise SyntaxError
x = 1
print eval("1+x") # 2
float
Return a floating point number constructed from a number or string x
Raise ValueError
print(float('100')) # convert a string to float
print(float(0b1111)) # convert a binary number to float
print(float(0o1777)) # convert a octal number to float
print(float(0xABCD)) # convert a hexical number to float
frozenset
Return a new frozenset object
s = frozenset([1, 2, 3, 4, 1])
print type(s), s # (1, 2, 3, 4)
hex
Convert an integer number (of any size) to a lowercase hexadecimal string
Raise TypeError
h = hex(100)
print(type(h), h) # str, '0x64'
input
return the result of the evaluated expression, equals to eval(raw_input())
If the input is not syntactically valid, a SyntaxError will be raised
l = input("Enter your input:") # 1+2
print l, type(l) # 3, int
l = raw_input("Enter your input:") # 1+2
print eval(l), type(l) # 3, str
int
return an integer object constructed from a number or string x, or return 0 if no arguments are given
Raise ValueError
print(int('100')) # convert a string to integer
print(int(0b1111)) # convert a binary number to integer
print(int(0o1777)) # convert a octal number to integer
print(int(0xABCD)) # convert a hexical number to integer
list
Return a list whose items are the same and in the same order as iterable’s items, iterable may be either a sequence, a container that supports iteration, or an iterator object
Raise TypeError
l = list([1, 2, 3, 4])
l = list(xrange(10))
l = list(iter(xrange(10)))
print(l)
long
Return a long integer object constructed from a string or number x
Raise ValueError
print type(long(10)) # long
print(long('100')) # convert a string to long
print(long(0b1111)) # convert a binary number to long
print(long(0o1777)) # convert a octal number to long
print(long(0xABCD)) # convert a hexical number to long
oct
Convert an integer number (of any size) to an octal string
Raise TypeError
o = oct(100)
print(type(o), o) # str, 0144
ord
Given a string of length one, return an integer representing the Unicode code point of the character
Raise TypeError
print(ord('a'))
print(ord(u'a'))
print(ord(u'\u2020'))
raw_input
return a string
When EOF is read, EOFError is raised
l = raw_input("Enter your input:") # 1+2
print l, type(l) # 1+2, 'str'
repr
Return a string containing a nicely printable representation of an object
str() is used for creating output for end user while repr() is mainly used for debugging and development. repr’s goal is to be unambiguous and str’s is to be readable
#!/usr/bin/python
print(str(10.0/3)) # 3.33333333333
print(repr(10.0/3)) # 3.333333333333335
import datetime
today = datetime.datetime.now()
print(str(today)) # 2018-10-12 00:32:14.820843
print(repr(today)) # atetime.datetime(2018, 10, 12, 0, 32, 14, 820843)
set
Return a new set object
s = set([1, 2, 3, 4, 1])
print type(s), s # (1, 2, 3, 4)
str
Return a string containing a nicely printable representation of an object
s = str(100); # convert an integer to string
print s # 100, str
tuple
Return a tuple whose items are the same and in the same order as iterable’s items
t = tuple(range(4))
print type(t), t # tuple, (0, 1, 2, 3)
unichar
Return the Unicode string
Raise ValueError
u = unichr(100)
print type(u), u
u = unichr(300)
print type(u), u
Reference