Differences between `input` and `raw_input` [dupli

问题:

This question already has an answer here:

• What's the difference between raw_input() and input() in python3.x? 6 answers

In a tutorial, I read that that there is a difference between input and raw_input. I discovered that they changed the behavior of these functions in the Python 3.0. What is the new behavior?

And why in the python console interpreter this

x = input()

Sends an error but if I put it in a file.py and run it, it does not?

回答1:

In python 2.x, raw_input() returns a string and input() evaluates the input in the execution context in which it is called

>>> x = input()
\"hello\"
>>> y = input()
x + \" world\"
>>> y
\'hello world\'

In python 3.x, input has been scrapped and the function previously known as raw_input is now input. So you have to manually call compile and than eval if you want the old functionality.

python2.x                    python3.x

raw_input()   --------------> input()               
input()  -------------------> eval(input())     

In 3.x, the above session goes like this

>>> x = eval(input())
\'hello\'
>>> y = eval(input())
x + \' world\'
>>> y
\'hello world\'
>>> 

So you were probably getting an error at the interpretor because you weren\'t putting quotes around your input. This is necessary because it\'s evaluated. Where you getting a name error?

回答2:

input() vs raw_input()

raw_input collects the characters the user types and presents them as a string. input() doesn\'t just evaluate numbers but rather treats any input as Python code and tries to execute it. Knowledgeable but malicious user could type in a Python command that can even deleted a file. Stick to raw_input() and convert the string into the data type you need using Python\'s built in conversion functions.

Also input(), is not safe from user errors! It expects a valid Python expression as input; if the input is not syntactically valid, a SyntaxError will be raised.

回答3:

Its simple:

1. raw_input() returns string values
2. while input() return integer values

For Example:

1.

x = raw_input(\"Enter some value = \")
print x

Output:

Enter some value = 123
\'123\'

2.

y = input(\"Enter some value = \") 
print y

Output:

Enter some value = 123
123

Hence if we perform x + x = It will output as 123123

while if we perform y + y = It will output as 246