CODEWITHSUNDEEP
python
Aj Entity
Aj Entity

Reputation: 4891

Checking for Errors

How do I set a value to only accept certain data in Python? Like I am making a code for a colour identifier. I want my variable to only accept up to FFFFFF any nothing greater than that. The base-16 characters pretty much...hex code.

The reason I am trying to do this is because if a user enters in a value like GGGGGG it will give them a Script Error, which actually makes me look incompetent (which I might be, but I do not want to look like I am). And also, if they enter in special characters like F1F2G% it will mess up too. In addition, if they leave the box blank, it also gives a Script Error.

I want to avoid those errors. Does anyone know of a good way?

Upvotes: 2

Views: 544

Answers (3)

Levon
Levon

Reputation: 143022

This is one approach assuming the input is a string:

import string

def check_HEX(input):
    for l in input:
        if l not in string.hexdigits:
            return False
    return True

gives:

print check_HEX('FFFFFF') # True
print check_HEX('FFFZFF') # False
print check_HEX(' ')      # False
print check_HEX('F1F2G%') # False

Upvotes: 1

ncmathsadist
ncmathsadist

Reputation: 4891

You can also use the regex facility in re. 

val = val.upper()
seeker = re.compile("^[0-9A-F]{1,6}$")

if seeker.search(val):
    hexCode = int(val, 16)
    # process a good value
else:
    #bail

Upvotes: 1

Amber
Amber

Reputation: 526603

try:
    val = int(hex_val, 16)
except ValueError:
    # Not a valid hex value

if val > int("FFFFFF", 16):
    # Value is too large

Upvotes: 11

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