What does placing \ at the end of a line do in python?

Question

I'm looking at the following piece of code:

totalDistance += \
      GetDistance(xCoords[i], yCoords[i],
                         xCoords[i+1], yCoords[i+1])

and can't understand what += \ means?

Answer 1

\ at the end of a line just indicates it will be continued on the next line as otherwise that (totalDist +=) would raise an error... (also important to note that there can be nothing after the slash ... not even whitespace)

+= just adds and assigns back

x = 1
x += 1 # x is now 2  (same as  x = x + 1)

Answer 2

The \ escapes the line return immediately following it (there should not be any character between the \ and the implicit \n).

There are also a few other exceptions; new lines are ignored when enclosed in the matching pairs of the following:

• []
• ()
• {}

In other words, the following are equivalent:

a= [1,2,3]
a = [1,
     2,
     3]

Answer 3

The combination \ followed by newline means line continuation. You can think of the \ as escaping the newline, so that it doesn't have it's usual meaning of "line ending".

In Python, you can often arrange the code so that \ is unnecessary, eg.

totalDistance += GetDistance(
                     xCoords[i], yCoords[i],
                     xCoords[i+1], yCoords[i+1])

here, the newlines don't end the line because they are inside the ()