backslashes in strings
Question:
When printinga a string containing a backslash, I expect the backslash (
test1 = "This is a test String?"
print(test1)
'This is a \ test String?'
test2 = "This is a '' test String?"
print(test2)
"This is a '' test String?"
What I expect is "This is a test String!" or "This is a '' test String!" respectively. How can I achieve that?
Answers:
You should add an extra backslash in your code before the replace:
test2 = "This is a '\' test String?"
test2.replace("?", "!")
"This is a '' test String!"
Two issues.
First case, you’re getting the representation not the string value. that’s a classic explained for instance here: Python prints two backslash instead of one
Second case, you’re escaping the quote unwillingly. Use raw string prefix in all cases (specially treacherous with Windows hardcoded paths where test becomes <TAB>est):
test2 = r"This is a '' test String?"
In the first case, it "works" because doesn’t escape anything (for a complete list of escape sequences, check here), but I would not count too much on that in the general case. That raw prefix doesn’t hurt either:
test1 = r"This is a test String?"
Python is actually doing what you expect – the confusion lies in the fact that you are using str.__repr__ to display the content of the string. If you print it, it looks ok:
In [17]: test1 = "This is a test String?"
[18]: test1
Out[18]: 'This is a \ test String?'
In [19]: print(test1)
This is a test String?
Python shows the string with a double backslash as a single backslash wouldn’t be an acceptable representation (i.e. it would mean you are escaping the character after the backslash)
When printinga a string containing a backslash, I expect the backslash () to stay untouched.
test1 = "This is a test String?"
print(test1)
'This is a \ test String?'
test2 = "This is a '' test String?"
print(test2)
"This is a '' test String?"
What I expect is "This is a test String!" or "This is a '' test String!" respectively. How can I achieve that?
You should add an extra backslash in your code before the replace:
test2 = "This is a '\' test String?"
test2.replace("?", "!")
"This is a '' test String!"
Two issues.
First case, you’re getting the representation not the string value. that’s a classic explained for instance here: Python prints two backslash instead of one
Second case, you’re escaping the quote unwillingly. Use raw string prefix in all cases (specially treacherous with Windows hardcoded paths where test becomes <TAB>est):
test2 = r"This is a '' test String?"
In the first case, it "works" because doesn’t escape anything (for a complete list of escape sequences, check here), but I would not count too much on that in the general case. That raw prefix doesn’t hurt either:
test1 = r"This is a test String?"
Python is actually doing what you expect – the confusion lies in the fact that you are using str.__repr__ to display the content of the string. If you print it, it looks ok:
In [17]: test1 = "This is a test String?"
[18]: test1
Out[18]: 'This is a \ test String?'
In [19]: print(test1)
This is a test String?
Python shows the string with a double backslash as a single backslash wouldn’t be an acceptable representation (i.e. it would mean you are escaping the character after the backslash)