Python · Syntax: indentation, comments, print

Python has no { } around blocks. A colon opens a block, and every line in that block is indented by the same amount. PEP 8 recommends 4 spaces. If the indentation is inconsistent you get an IndentationError, so here indentation is syntax, not just style.

Comments start with # and run to the end of the line. A string on its own line (often triple-quoted) is not a comment; it is an expression whose value is thrown away. At the top of a function, though, it becomes the docstring.

print() takes any number of values. It also has keyword arguments:

• sep: what goes between values (default is a space)
• end: what goes after the last value (default is a newline)

# a block is opened by ":" and defined by indentation
x = 7
if x > 5:
    print("x is big")       # inside the if-block
    print("still inside")
print("outside the block")

print("a", "b", "c")             # default sep=" "
print("a", "b", "c", sep="-")    # custom separator
print("no newline", end=" | ")
print("same line")

Output:

x is big
still inside
outside the block
a b c
a-b-c
no newline | same line