Python 3 语法错误无效语法

Question

With this code I am trying to generate simple multiplication tables. The program should ask for input and multiple that number in a range up to 15 and the generate the multiplication table for the number. After the if_name_ == ' main ': line I end up with a syntax error after the colon. I normally program in python 2, so python 3 is a bit new to me but I'm not sure what the difference is. Below I have listed the short but full code. Any help would be much appreciated.

'''Multiplication Table'''

def multi_table(a):
    for i in range(1,16):
        print(' {0} x {1} = {2} '.format(a, i, a*i))



if_name_ == '_main_':
    a = input('Enter a number: ')
    multi_table(float(a))

Answer 1

if_name_ == '_main_':
    a = input('Enter a number: ')
    multi_table(float(a))

should be :

if __name__ == "__main__":
    a = input('Enter a number: ')
    multi_table(float(a))

Notice that both variable __name__ and __main__ has two underscores around them and that there must be a space between the if keyword and the start of the condition.

Answer 2

As @Maroun Maroun said right, it has to be if __name__ == "__main__" . But you wont need it. Just write it at the bottom :

'''Multiplication Table'''

def multi_table(a):
    for i in range(1,16):
        print(' {0} x {1} = {2} '.format(a, i, a*i))

a = input('Enter a number: ')
multi_table(float(a))

Should work, too.

EDIT: In the official docs :

https://docs.python.org/3/library/ main .html

if __name__ == "__main__":

Answer 3

It might also be possible that the "invalid syntax" is because means you have forgotten to close a parenthesis on the previous line of code.

Answer 4

In the example provided, (i) there's a space missing after if , and (ii) the symbol's name should have two pairs of underscores: __name__ . If these two corrections resolve your problem, great.

But in case you still have another more mysterious unresolved syntax error, then read on...

Recently I encountered a very similar error message, and it was hard to root-cause, since the error message seems to point in the wrong direction. The error seems to indicate that the syntax error lies at the end of the if statement. However, with Python 3.x I noticed that in case a parentheses mismatch error happens in a python source file, the error might be reported at the beginning of the next block rather than where the mismatch actually occurs.

It's worth checking for mismatched parentheses in the entire source code file, prior to the if statement. Check if all your ( s are matched by a closing ) .

Answer 5

Same problem. It shows either main or name is undefined