python全局变量的修改 线程共享全局变量

箭头指向不变，而修改里面的值，则可不加global

如果箭头指向的方向变，则必须加global

至于哪些可变哪些不可变，要看具体的数据类型 数字，字符串、元组不可变，其它可变

num = 100def test():global numnum += 100print(num)test()print(num)

import threadingimport timeg_num = 100def test1():global g_numg_num += 11print("---------test1--- g_num =%d----" % g_num)def test2():print("---------test2--- g_num =%d----" % g_num)def main():t1 = threading.Thread(target=test1)t2 = threading.Thread(target=test2)t1.start()time.sleep(1)t2.start()time.sleep(1)print("----in main Thread g_num = %d" % g_num)if __name__ == "__main__":main()