Python Learning Path-the third day-function

Function

• Definition of a function keyword: def

• Using the global statement makes it clear that the variable is defined outside the block

• Example: (The value of X is 2 after the function has finished running)

#!/usr/bin/python# Filename: func_global.pydef func():    global x    print ‘x is‘, x    x = 2    print ‘Changed local x to‘, xx = 50func()print ‘Value of x is‘, x

• You can give the shape a default value, the default parameter is immutable, and only those parameters at the end of the formal parameter list can have default parameter values, that is, you cannot declare a function parameter, declare a parameter with a default value, and then declare that there is no default
  The formal parameter of the value. This is because the value assigned to the parameter is assigned according to the position. For example, Def func (A, b=5) is valid, but def func (a=5, b) is not valid.

• Example:

#!/usr/bin/python# Filename: func_default.pydef say(message, times = 1):    print message * timessay(‘Hello‘)say(‘World‘, 5)

HelloWorldWorldWorldWorldWorld

• Key parameter, it is interesting to assign a value based on the specified parameter name, without having to assign a value by position each time

• Example:

#!/usr/bin/python# Filename: func_key.pydef func(a, b=5, c=10):    print ‘a is‘, a, ‘and b is‘, b, ‘and c is‘, cfunc(3, 7)func(25, c=24)func(c=50, a=100)

Operation Result:

$ python func_key.pya is 3 and b is 7 and c is 10a is 25 and b is 5 and c is 24a is 100 and b is 5 and c is 50

• The pass statement represents an empty block of statements in Python. Like in the java/c++;

• Unless you provide your own return statement, each function contains a return none statement at the end

• Document String docstrings, all it does is grab the __doc__ property of the function and show it to you neatly.

#!/usr/bin/python# Filename: func_doc.pydef printMax(x, y):    ‘‘‘Prints the maximum of two numbers.    The two values must be integers.‘‘‘    x = int(x) # convert to integers, if possible    y = int(y)    if x > y:        print x, ‘is maximum‘    else:        print y, ‘is maximum‘printMax(3, 5)print printMax.__doc__

Python Learning Path-the third day-function