exec with n does not work

Question

I’m trying to use the function exec in a code that has \n, but it seems that this function does not support \n

a = '''
open('test.txt', 'a').write('Hello, world\n')
'''
exec(a) 

Error:

SyntaxError: EOL while scanning string literal

Is there any way to make it work?

Answer 1

Yes - when the Python compiler reads the string that goes inside the vailable a, he already plays the \n to be a line change - then the code exec will compile at that point:

a = '''
open('test.txt', 'a').write('Hello, world\n')
'''
exec(a) 

is seen this way:

open('test.txt', 'a').write('Hello, world
')

What is a syntax error.

You resolve easily by escaping \ with an extra bar, or using a raw string:

a = r'''
open('test.txt', 'a').write('Hello, world\n')
'''
exec(a) 

(note the "r" prefixing the triple quotes in the a =) - this makes the "" in a is passed literately to the string, and when the compiler interprets the snippet write('Hello, world\n') inside, the n will be expanded, but this time in the right place.

Answer 2

You’re trying to use exec specifically? Or could Voce write au document directly?

Like this: open('test.txt', 'a').write('Hello, world\n')

Any way, no comment '''. This is why Voce gets the error

Edited for your comment:

a = open('test.txt', 'a').write('Hello, world\n')
exec(str(a))