python基础__全局变量

 1 value='c919'
 2 
 3 def sky1():
 4     global value
 5     value = '波音747'
 6     return value
 7 
 8 def sky2():
 9     value = '金门石头829'
10     return value
11 
12 sky1()
13 print(value) # 波音747
14 sky2() # 函数中没有global，全局变量不会被改变 
15 print(value) # 波音747

 1 import threading
 2 value='歼2025'
 3 
 4 def sky1():
 5     global value
 6     value = '猛禽F-22'
 7     return value
 8 
 9 def sky2():
10     if value=='猛禽F-22':
11         print("东风829发射")
12 
13 thread2025 = threading.Thread(target=sky1)
14 thread2025.start()
15 sky2()#主线程中判断已被子线程修改过的全局变量value