eval SyntaxError: invalid syntax in python

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Question :

eval SyntaxError: invalid syntax in python

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?

Asked By: showkey

||

Answer #1:

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'
Answered By: suhailvs

Answer #2:

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 By: Martijn Pieters

Answer #3:

You can you this expression.

eval('"x"+str(i)+"="+"123"')
Answered By: user3164787

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