tf4. Placeholder

import sysprint(sys.version)'''3.5.3 |Continuum Analytics, Inc.| (default, May 15 2017, 10:43:23) [MSC v.1900 64 bit (AMD64)]'''import tensorflow as tf#在 Tensorflow 中需要定义 placeholder 的 type ，一般为 float32 形式input1 = tf.placeholder(tf.float32)input2 = tf.placeholder(tf.float32)# mul = multiply 是将input1和input2 做乘法运算，并输出为 outputouput = tf.multiply(input1, input2)with tf.Session() as sess:    print(sess.run(ouput, feed_dict={input1: [7.], input2: [2.]}))# [ 14.]