tf Variable does not change value? [duplicate]

Question

i just want to change the value of a tf.Variable with .assign(), but it always prints "0" ?

import tensorflow as tf

session = tf.Session()

var = tf.Variable(0, "myVar")

session.run(tf.initialize_all_variables())

var.assign(var + 1)
print session.run(var)

var.assign(var + 1)
print session.run(var)

Edit: this works

import tensorflow as tf

session = tf.Session()

var = tf.Variable(0, "myVar")

session.run(tf.initialize_all_variables())

add = var.assign(var + 1)
print session.run(add)

print session.run(add)

Answer 1

assign only creates the operation to change the variable, you have to run it:

import tensorflow as tf

session = tf.Session()

var = tf.Variable(0, "myVar")

session.run(tf.initialize_all_variables())

session.run(var.assign(var + 1))
print session.run(var)

session.run(var.assign(var + 1))
print session.run(var)