python基础-内置函数(1)

python 提供了很多的内置函数。

一、数值处理相关函数：

　　1、取绝对值：abs()

def abs(*args, **kwargs): # real signature unknown
    """ Return the absolute value of the argument. """
    pass

　　2、转二进制：bin()

def bin(*args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
    """
    Return the binary representation of an integer.
    
       >>> bin(2796202)
       '0b1010101010101010101010'
    """

　　3、转八进制：oct()

def oct(*args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
    """
    Return the octal representation of an integer.
    
       >>> oct(342391)
       '0o1234567'
    """

　　4、转十六进制：hex()

def hex(*args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
    """
    Return the hexadecimal representation of an integer.
    
       >>> hex(12648430)
       '0xc0ffee'
    """

　　5、取最大值：max()

def max(*args, key=None): # known special case of max
    """
    max(iterable, *[, default=obj, key=func]) -> value
    max(arg1, arg2, *args, *[, key=func]) -> value
    
    With a single iterable argument, return its biggest item. The    使用一个可迭代的参数，返回其中最大值的项
    default keyword-only argument specifies an object to return if
    the provided iterable is empty.
    With two or more arguments, return the largest argument.
    """

　　6、取最小值：min()

def min(*args, key=None): # known special case of min
    """
    min(iterable, *[, default=obj, key=func]) -> value
    min(arg1, arg2, *args, *[, key=func]) -> value
    
    With a single iterable argument, return its smallest item. The
    default keyword-only argument specifies an object to return if
    the provided iterable is empty.
    With two or more arguments, return the smallest argument.
    """

 　　7、浮点函数和整型函数：float()，int()

s='11.3432'     #字符串
s1=int(float(s))    #先把字符串转成浮点型，然后再转为整型
print(s1)

结果： 11

 　　8、求和函数：sum()

s=[11,22,33,44,5]
print(sum(s))

 　　9、指数函数：pow()

s=pow(2,10)
print(s)

结果：1024

　　10、四舍五入函数：round()

r=round(1.8)
print(r)

　　11、排序：sorted()

li=[11,2,3,44,5]
r=sorted(li)
print(r)

结果：[2, 3, 5, 11, 44]

 

二、返回是布尔值的函数：

　　1、所有元素为真，函数返回真：all()

def all(*args, **kwargs): # real signature unknown
    """
    Return True if bool(x) is True for all values x in the iterable.
    
    If the iterable is empty, return True.
    """

　　2、有一个元素为真，函数返回真：any（）

def any(*args, **kwargs): # real signature unknown
    """
    Return True if bool(x) is True for any x in the iterable.
    
    If the iterable is empty, return False.
    """

 　　3、返回对象是否可调用：callable()

def callable(i_e_, some_kind_of_function): # real signature unknown; restored from __doc__
    """
    Return whether the object is callable (i.e., some kind of function).
    
    Note that classes are callable, as are instances of classes with a
    __call__() method.
    """

　　4、判断对象是否是指定类的实例：isinstance()

s = ['Spring', 'Summer', 'Fall', 'Winter']
print(isinstance(s,list))

 

三、编译和执行代码

　　1、把字符串编译成python代码：compile()

s="print(123)"
r=compile(s,'<string>',"exec")
exec(r)

　　2、执行代码：exec() 和 eval()

　　　　两者区别：a、exec()可以执行python 代码，也可以执行表达式，而eval() 只能执行表达式

　　　　　　　　　b、exec()只是执行，没有返回值，而eval() 有返回值

s="print(123)"
r=compile(s,'<string>',"exec")
exec(r)
exec("print('10*10')")
r=eval("8*8")
print(r)