[FIXED] What does a backslash at the end of a line mean?

Issue

In this exercise i was supposed to capitalise everything that needs to be capitalised like the "I"s or the first letter of a new sentence etc..

In my attempt i tried to use "=", but python doesn't allow that. So i just looked at the solutions. In the following solution the author uses " + \ " (with comment), can someone tell me what that is what that does? I tried to put them in one line but then the IDE would give me an error message.

def capitalize(s):
    result = s.replace(" i ", " I ")
    if len(s) > 0:
        result = result[0].upper() + \ # this part, what is this + \? if i put them in one line, 
                                       # the IDE would give me an error message
                 result[1 : len(result)]
    pos = 0

    while pos < len(s):
        if result[pos] == "." or result[pos] == "I" or result[pos] == "?":
            pos = pos + 1

            while pos < len(s) and result[pos] == " ":
                pos = pos + 1

            if pos < len(s):
                result = result[0 : pos] + \
                    result[pos].upper() + \
                    result[pos + 1 : len(result)]
        pos = pos + 1

    return result

def main():
    s = input("Enter some text: ")
    capitalized = capitalize(s)
    print("It is capitalized as:", capitalized)

main()

Solution

New lines often signal the end of a statement to the python interpreter.
There are however a few exceptions to this rule:

Semicolon

x=5; y=6; z=x+y; print(z);

In the code above, the semicolon (;) is used to signal the end of a statement, and thus allows multiple statements to be written on a single line.

New line

# This is a comment before a statement
x=5
y=6
z=x+y
print(z)  # This is a comment after a statement

The code above makes use of the new line to separate statements from each other, and is legitimate python code. Also note that you can place a comment before a statement, however, a new line separates the comment from the statement. Note: A semicolon cannot be used at the end of a comment to separate the comment from a statement. eg. # This is a comment ; x=5; y=6;
However, a comment can be placed on the same line as a statement provided it is placed at the end of the statement. eg. print(z) # This is a comment after a statement.

Backslash

x = 5
y = 6
z = x + \
    y       # comment after statement is ok
print(z)

A backslash \ can be used to carry a statement over to another line(s) provided:

• There are no other characters (including spaces) on the same line, after the backslash.
• The subsequent lines are indented appropriately
• Comments occur at the end of the statement, not in between.

Brackets

x = 5
y = 6
z = (x +     # comments can happen in the middle of a statement
    y)       # comment after statement is ok
print(z)

a = [5,      # comments can happen here too
     6,
     7,
     8]

This is an example of how brackets () + [] tend to break the rules a bit. Whereby you can place comments at the end of a line, but within a statement.

There are probably some other rules that I have not thought of, but the reason you are getting an error in your example above is because you are trying to place a comment in the middle of a statement. I hope this clarifies the issue somewhat.

Answered By - ScottC

Answer Checked By - Marilyn (PHPFixing Volunteer)