Question

I wrote a function that needs to do 3 checks and if one of the tests fails it should return an exception of type of LookupError, but it doesn’t work.
(*verify_checksum is another function)

def check_datagram(datagram, src_comp, dst_app):
    try:
        src_comp==datagram[0:16]
    except LookupError:
        return "Mismatch in src_comp"
    try:
        dst_app==datagram[40:48]
    except LookupError:
        return "Mismatch in dst_app"
    try:
        verify_checksum(datagram)
    except False:
        return "Wrong checksum"
    return True

For example:

Input:

check_datagram("1111000000001111000011111111000001010101101010101111111111111111000000001111111100000000","0000111100001111", "11110000")

Expected output:

"Mismatch in dst_app"

Answer 1

def check_datagram(datagram, src_comp, dst_app):
    if src_comp != datagram[0:16]:
        raise LookupError("Mismatch in src_comp")
    if dst_app != datagram[40:48]:
        raise LookupError("Mismatch in dst_app")
    if not verify_checksum(datagram):
        raise LookupError("Wrong checksum")
    return True # redundant?