python基礎--函數

一、定義函數

# 全局變量和局部變量名字相同
str = "aaa" # 定義了一個全局變量
def myPrint():
    #global str#：使用global對一個全局變量的聲明
    str = "bbb"
    print(str)
    
myPrint() #結果：bbb
print(str) #結果：aaa

 

二、缺省參數：

def myPrint(name, age = 10):
    print(name)
    print(age)
    
myPrint("zs", 20)
myPrint("zs")
print("=" * 10)
myPrint(name = "zs", age = 30)
myPrint(name = "zs")

 

三、不定長參數

def myPrint(a, *params):
    print(a)
    print(params) # (10, 20, 30)
    
myPrint("zs", 10, 20, 30)

def myPrint(a, **params):
    print(a)
    print(params)
    for i in params:
        print(i)
    
myPrint("zs", name='zs', age = 20)

 

四、拆包

def myPrint(a, *args, **params):
    print(a)
    print(args)
    print(params)
    
args = (1, 2, 3);
params = {'name':'zs', 'age':20};
myPrint("zs", *args, **params)

打印結果：
zs
(1, 2, 3)
{'name': 'zs', 'age': 20}

 

五、匿名函數

def test(a, b, fn):
    return fn(a, b)
    
print(test(10, 20, lambda x,y:x+y))
print(test(10, 20, lambda x,y:x-y))
print(test(10, 20, lambda x,y:x*y))

 

def test(a, b, fn):
    return fn(a, b)

fn_new = input("請輸入 lambda表達式：")
    
print(test(10, 20, eval(fn_new)))