#定義varible必須初始化
import tensorflow as tf
state=tf.Variable(0,name='counter')
one=tf.constant(1)

new_value=tf.add(state,one)
update=tf.assign(state,new_value)#new_value載入到state相當於賦值

init=tf.initialize_all_variables()#must have if define variable
with tf.Session() as sess:
    sess.run(init)
    for _ in range(3):
        sess.run(update)
        print(sess.run(state))