Python:Control structures

Most flow control is standard. Indentation defines the code block to execute. You must be strict, all indents must be the same in a block, a mix of spaces and tabs is not allowed (unless each line uses the same mix).

You can define you own Python:Functions too.

if expression:
    block
elif expression:
    block
else:
    otherblock

for var1 in itterable:  # keys if itterable is a dict
    block
    if somethinghappens:
        break

while expression:
    block
    if somethinghappens:
        continue

break

Stop looping immediately. Jump to the next statement after the loop.

continue

Stop the current iteration immediately and jump the the top of the loop, do the next iteration.

pass

No operation, use e.g. to avoid negative tests

var1 = ( x if <condition> else y )

No operation, use e.g. to avoid negative tests

Exception handling

To catch exceptions:

try:
    blockthatmaythowexception
except <exception>:
    blockifexceptionisthrown
else:
    blockifNOexceptionisthrown

NOTE: elif is not allowed here.

Specifying an exception is optional but highly recommended (Easier to ask for forgiveness than permission aka EAFP) and it is said to be faster. However, take care you don't forgive real faults.

The exception-types can be found in the python docs

except NameError

The variable does not exist

except KeyError

The key does not exist in the dict

except IndexError

The index does not exist in the list