入门的时候Python所有 教程都是从第一个hello world开始

print("  hello world ")
print()

print是系统内置的一个函数

print(print)     #<built-in function print>  print就是一个函数

回顾一个函数定义 f(x,y,z)

def  myfunc():
       pass
       

def  func2(p2, p2):
        pass

def :定义函数关键字

myfunc:函数名

fun2(p2,p2): 函数func2有两个参数p1,p2

函数print的定义是怎么样的呢？

def print(self, *args, sep=' ', end='\n', file=None): # known special case of print
    """
    print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
    
    Prints the values to a stream, or to sys.stdout by default.
    Optional keyword arguments:
    file:  a file-like object (stream); defaults to the current sys.stdout.
    sep:   string inserted between values, default a space.
    end:   string appended after the last value, default a newline.
    flush: whether to forcibly flush the stream.
    """
    pass

 """
    print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
    
    Prints the values to a stream, or to sys.stdout by default.
    Optional keyword arguments:
    file:  a file-like object (stream); defaults to the current sys.stdout.
    sep:   string inserted between values, default a space.
    end:   string appended after the last value, default a newline.
    flush: whether to forcibly flush the stream.
    """

• print函数支持输出多个数据 print("hello","world") 会输出两个内容，然后以空格分隔

sep: string inserted between values, default a space.

print("hello","world")   
# hello world

print("a","b","c",1,[2],True,False)
# a b c 1 [2] True False

• 结束符号默认是换行

end: string appended after the last value, default a newline.

print("\n\n\n\n")
print("abc",end="")  #换行符号为空，不会产生新行。因此abcdef为一行输出
print("def")
#abcdef

参数与参数之间的分隔符 sep默认是空格

sep: string inserted between values, default a space.

print('hello', 'world', sep='\n')  # 这时hello world会分成两行输出

hello
world

print('hello', 'world', sep=' -----')
hello -----world

print('/home', 'user', 'documents', sep='/')    #    /home/user/documents
print('', 'home', 'user', 'documents', sep='/')  #   /home/user/documents
print(1, 'Python Tricks', 'Dan Bader', sep=',')  # node -> child -> child
print('node', 'child', 'child', sep=' -> ')            # 1,Python Tricks,Dan Bader

使用print输出小动画

import time

num_seconds = 3
for countdown in reversed(range(num_seconds + 1)):
    if countdown > 0:
        print(countdown, end='...')
        time.sleep(1)
    else:
        print('Go!')

所以我们用print输出时，可以有很多种选项，不需要

print( "aaa" + str(1))
print("abc",1 ) #即可