将\\放在行尾在python中有什么作用？

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 ()