eval SyntaxError: invalid syntax in python [duplicate]

Question

I want to assign :

x0='123'    
x1='123'    
x2='123'    
x3='123'    
x4='123'    
x5='123'    
x6='123'    
x7='123'    
x8='123'    
x9='123'

I write the code to express that i can get the output of a string 123 when input x1 or x8 .

for i in range(0,10):
    eval("x"+str(i)+"='123'")

Traceback (most recent call last):
File "<stdin>", line 2, in <module>
File "<string>", line 1
  x0='123'
  ^
SyntaxError: invalid syntax

How i can do that way?

_{Do not ever use eval (or exec) on data that could possibly come from outside the program in any form. It is a critical security risk. You allow the author of the data to run arbitrary code on your computer. If you are here because you want to create multiple variables in your Python program following a pattern, you almost certainly have an XY problem. Do not create those variables at all - instead, use a list or dict appropriately.}

Obligatory link: Keep data out of your variable names. Don't use eval to create variables. Use a list or dictionary instead. — Martijn Pieters
– Martijn Pieters, Commented Mar 21, 2014 at 12:20
eval() only allows for expressions. Assignment is not an expression but a statement. — Martijn Pieters
– Martijn Pieters, Commented Mar 21, 2014 at 12:21
Use exec for statements not eval, as Martijn said use a list/dictionary. — Ashwini Chaudhary
– Ashwini Chaudhary, Commented Mar 21, 2014 at 12:21

Djaouad · Accepted Answer · 2021-02-09 15:09:15Z

55

For dynamic execution of statements use the exec function:

>>> exec('y = 3')
>>> y
3

eval usage: eval(expression).

The expression argument is parsed and evaluated as a Python expression.

e.g.:

>>> s = 3
>>> eval('s == 3')
True
>>> eval('s + 1')
4
>>> eval('s')
3
>>> eval('str(s) + "test"')
'3test'

edited Feb 9, 2021 at 15:09

Djaouad

22.8k4 gold badges37 silver badges57 bronze badges

answered Mar 21, 2014 at 12:28

suhailvs

21.9k15 gold badges104 silver badges104 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Martijn Pieters · Accepted Answer · 2014-03-21 12:22:30Z

27

eval() only allows for expressions. Assignment is not an expression but a statement; you'd have to use exec instead.

Even then you could use the globals() dictionary to add names to the global namespace and you'd not need to use any arbitrary expression execution.

You really don't want to do this, you need to keep data out of your variable names and use a list or dictionary instead:

x = ['123'] * 10

would give you a list you can address as x[0], x[1], etc. without having to execute arbitrary expressions.

answered Mar 21, 2014 at 12:22

Martijn Pieters

1.1m326 gold badges4.2k silver badges3.4k bronze badges

Comments

Exa · Accepted Answer · 2015-06-25 09:09:14Z

-3

You can you this expression.

eval('"x"+str(i)+"="+"123"')

edited Jun 25, 2015 at 9:09

Exa

4,1168 gold badges46 silver badges63 bronze badges

answered Jun 25, 2015 at 7:31

user3164787

171 silver badge7 bronze badges

Collectives™ on Stack Overflow

eval SyntaxError: invalid syntax in python [duplicate]

3 Answers 3

Comments

Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Linked

Related