Using re.match in an If statement in Python

Question

I am setting up a function in Python to receive a date in the format MM/DD/YYYY, then validate it with a regular expression. This is what I have right now:

def getdate():
    date = raw_input("Please enter the date completed (MM/DD/YYY): ")
    if re.match(r"\d{2}/\d{2}/\d{4}", date)
        break
    else:
        print "Incorrect date format"
        getdate()

The system keeps returning a syntax error pointing at the close parentheses in the "if" line. I can't seem to figure out exactly what it is considering a syntax error. I have also tried this with no success:

def getdate():
    date = raw_input("Please enter the date completed (MM/DD/YYY): ")
    valid = "(\d{2}/\d{2}/\d{4})"
    if re.match(valid, date)
        break
    else:
        print "Incorrect date format"
        getdate()

This also returns the same error.

Thanks.

Rohit Jain · Accepted Answer · 2013-10-11 16:51:40Z

2

You're missing the colon:

if re.match(r"\d{2}/\d{2}/\d{4}", date):  # <-- colon needs to be here

P.S: Please don't use recursion to ask for repetitive inputs. You might end up blowing the stack. Better use a loop. Also, devise some way to allow users only a certain number of attempts, to avoid the infinite loop.

answered Oct 11, 2013 at 16:51

Rohit Jain

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1 Comment

SimplyOmnipotent Over a year ago

I cannot believe I missed that.... That is embarrassing. Thank you. It never fails to have someone else look at your code... Thanks for the suggestion too. I see what you mean. I will fix that.

score 1 · Accepted Answer · 2013-10-11 16:56:48Z

1

You need a colon at the end:

if re.match(r"\d{2}/\d{2}/\d{4}", date):
#                               here --^

Python uses colons to end statements.

Also, as @RohitJain stated, using recursion to ask for repeated input is bad practice. You might want to make your code like this:

def getdate():
    date = raw_input("Please enter the date completed (MM/DD/YYY): ")
    valid = "(\d{2}/\d{2}/\d{4})"
    while not re.match(valid, date):
        print "Incorrect date format"
        date = raw_input("Please enter the date completed (MM/DD/YYY): ")
    return date

This new code uses a loop that runs until the input meets the specifications (namely, re.match returns with a match).

edited Oct 11, 2013 at 16:56

answered Oct 11, 2013 at 16:51

user2555451

1 Comment

SimplyOmnipotent Over a year ago

Oh thank you very much for the suggestion! Using a while loop vice an if statement is genius!

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