CODEWITHSUNDEEP
pythonif-statementbooleanboolean-expression
Matt
Matt

Reputation: 3557

Can't find the boolean logic to make this work

I'm trying to make the condition that if the [0][0] entry in the array is not equal to 1 or 2 the program prints an error message. I can't get it to work, and I know it's because I can't get the logic correct.

try:
    with open(input_script) as input_key:
        for line in input_key.readlines():
            x=[item for item in line.split()]
            InputKey.append(x)
    if InputKey[0][0] == 1 or 2:     #This is where my condition is being tested.
        print '.inp file succesfully imported' #This is where my success (or fail) print comes out.
    else:
        print 'failed'
except IOError:
    print '.inp file import unsuccessful. Check that your file-path is valid.'

Upvotes: 0

Views: 88

Answers (2)

Rohit Jain
Rohit Jain

Reputation: 213213

Your if condition is evaluated as:

if (InputKey[0][0] == 1) or 2:

which is equivalent to:

if (InputKey[0][0] == 1) or True:

which will always evaluated to True.

You should use:

if InputKey[0][0] == 1 or InputKey[0][0] == 2:

or

if InputKey[0][0] in (1, 2):

Note that, if your InputKey[0][0] is of type string, you can convert it to int using int(InputType[0][0]), else it won't match with 1 or 2.

Apart from that, your for loop can be modified as:

for line in input_key.readlines():         
    # You don't need list comprehension. `line.split()` itself gives a list
    InputKey.append(line.split())

Upvotes: 2

TerryA
TerryA

Reputation: 59974

if InputKey[0][0] == 1 or 2: is the same as:

(InputKey[0][0] == 1) or (2)

And 2 is considered True (bool(2) is True), thus this will statement will always be True.

You want python to interpret this as:

InputKey[0][0] == 1 or InputKey[0][0] == 2

Or even:

InputKey[0][0] in [1, 2]

Upvotes: 2

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