python自定义函数_python语言定义一个函数

• python语言很精简，定义函数不用大括号，根据换行格式确定函数语句是否结束:

def sum_num(x, y):
sumN = 0
for i in range(x,y+1):
sumN += i
return sumN

print(sum_num(1, 3))   >>>>>>>>>>>6

• 定义一个空函数，用pass占位语句：

def nop(x):

pass

• 参数检查：

def sum_num(x, y):
if not isinstance((x, y), (int, float)):
raise TypeError('参数错误')
sumN = 0
for i in range(x,y+1):
sumN += i
return sumN

print(sum_num(9, '78'))   >>>>>>>>>>>TypeError: 参数错误

• 返回值若有多个，组成一个tuple返回：

import math
def move(x, y, step, angle=0):
nx = x + step * math.cos(angle)
ny = y + step * math.sin(angle)
return nx, ny

t = move(0, 0, math.pi/4, 1.414)
print(t)   >>>>>>>>>>>(4.122643568127262, 7.775763385488835)