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Bit of help with Python
Basically, I want to be able for a user to input a string that includes the variables in my script (which they will know) and for them to be able to affect the script: For example:
i = 1
raw_input("Enter what you want to do to the variable 'i': ")
# some code that allows them to change the i variable
print i #the 'new' i
So if someone typed in i=i+5 or i= i*3 It would output 6 and 3..
Thanks in advance.
EDIT: Well techb's method is definitley a lot easier :P
The easiest way I can think of doing this is to use a regular expression to check if the string is of the correct form and then parse that string if the regex matches.
i = 1
str = raw_input("Enter what you want to do to the variable 'i': ")
# regular expression to match strings valid strings, e.g. "i=i+3" and " i = 4 / i "
regex = re.match("[ ]*i[ ]*=[ ]*(i[ ]*[\+\-\*\/][ ]*[0-9]+|[0-9]+[ ]*[\+\-\*\/][ ]*i)[ ]*", str)
if regex:
# get the individual parts of the string - operator, number, what order they were entered (i-2 or 2-i)
# could use regex:
operator = re.search("[\+\-\*\/]", str).group(0)
# or just iterate through string:
for i in str:
if i == "+" or i == "-" or i == "*" or i == "/":
operator = i
...
Note that eval only handles expressions, and exec only handles statements.
Check out this for better clarification.