38

I want to check whether the given string is single- or double-quoted. If it is single quote I want to convert it to be double quote, else it has to be same double quote.

bluish
  • 26,356
  • 27
  • 122
  • 180
Kumar
  • 769
  • 2
  • 7
  • 5
  • 7
    I'm not convinced everyone is interpreting your question the way you intended. Do these strings contain these single and double quotes *as part of the content*? The best way to explain your question would be to include some examples of what input you have, how you'd like the output to appear, etc. If at all possible, copy and paste from an actual Python console session so there will be no way we can mistake what you mean. – Peter Hansen Dec 16 '09 at 02:16
  • `black` formatter will do that automatically for you (unless there's a good reason not to). – GiM Nov 26 '21 at 19:36

7 Answers7

26

There is no difference between "single quoted" and "double quoted" strings in Python: both are parsed internally to string objects.

I mean:

a = "European Swallow"
b = 'African Swallow'

Are internally string objects.

However you might mean to add an extra quote inside an string object, so that the content itself show up quoted when printed/exported?

c = "'Unladen Swallow'"

If you have a mix of quotes inside a string like:

a = """ Merry "Christmas"! Happy 'new year'! """

Then you can use the "replace" method to convert then all into one type:

a = a.replace('"', "'")

If you happen to have nested strings, then replace first the existing quotes to escaped quotes, and later the otuer quotes:

a = """This is an example: "containing 'nested' strings" """
a = a.replace("'", "\\\'")
a = a.replace('"', "'")
mkrieger1
  • 19,194
  • 5
  • 54
  • 65
jsbueno
  • 99,910
  • 10
  • 151
  • 209
  • thank you first Actually am getting the the single quote string,double quoted strings dynamically and also am using urljoin(dublequote,singlequote) so here i facing problem the output is combination both but i need it as single – Kumar Dec 15 '09 at 12:29
  • 23
    When using `json`, it makes a LOT of difference between a string in `' ' ` and `" ".` – CKM Apr 27 '17 at 12:47
  • 4
    `json.dumps('dog')` ouputs `'"dog"'` to the file but I want `"dog"`. How to do that? – CKM Apr 27 '17 at 13:16
  • 2
    `json.dumps` create a Python string - if you are viewing it on the interactive mode, you will see the extra quotes around "dog" -, but if yu write that to a file (or use `json.dump` directly, a single layer of quotation is used. If you need zero quotes, you shoul strip them manually after json serialization. – jsbueno Apr 27 '17 at 19:46
  • 1
    @jsbueno yes, but json.loads('dog') will complain about single quotes as it's expecting double quoted strings (which is also defined in rfc7159). – daniel_of_service Jul 22 '18 at 10:49
22

Sounds like you are working with JSON. I would just make sure it is always a double quoted like this:

doubleQString = "{0}".format('my normal string')
with open('sampledict.json','w') as f:
    json.dump(doubleQString ,f)

Notice I'm using dump, not dumps.

Sampledict.json will look like this:

"my normal string"
Joshua Swain
  • 571
  • 2
  • 4
  • 22
MadsVJ
  • 678
  • 6
  • 19
  • 2
    This is a great answer, and `json.dumps` will return the string if you'd rather not have to export to a file. – jlansey Aug 20 '19 at 00:05
  • 1
    The double quotes are the output of json.dump/dumps - regardless of the `.format` call. The first line in your snippet is a no-operation: Python strings are Python strings, regardless of the surrouding quotes used when typing the literal. (And the default representation of strings uses single-quotes - " ' " ) – jsbueno Mar 10 '20 at 13:04
6

In my case I needed to print list in json format. This worked for me:

f'''"inputs" : {str(vec).replace("'", '"')},\n'''

Output:

"inputs" : ["Input_Vector0_0_0", "Input_Vector0_0_1"],

Before without replace:

f'"inputs" : {vec},\n'

"inputs" : ['Input_Vector0_0_0', 'Input_Vector0_0_1'],
KocT9H
  • 299
  • 1
  • 4
  • 14
5

The difference is only on input. They are the same.

s = "hi"
t = 'hi'
s == t

True

You can even do:

"hi" == 'hi'

True

Providing both methods is useful because you can for example have your string contain either ' or " directly without escaping.

Brian R. Bondy
  • 339,232
  • 124
  • 596
  • 636
  • Likewise, there is also no difference between the regularly-quoted string (`"foo"`) and triple-quoted string (`"""foo"""`). – Mike D. Dec 15 '09 at 13:46
  • @Brain `json.dumps('dog')` ouputs `'"dog"'` to the file but I want `"dog"`. How to do that? – CKM Apr 27 '17 at 13:17
4

In Python, there is no difference between strings that are single or double quoted, so I don't know why you would want to do this. However, if you actually mean single quote characters inside a string, then to replace them with double quotes, you would do this: mystring.replace('\'', '"')

Ben Hayden
  • 1,349
  • 9
  • 15
  • 2
    I like `string.replace("'", '"')` slightly better—it has a nice alternating pattern of quotes in it :-). – Alok Singhal Dec 15 '09 at 12:22
  • thank u so much thank you first Actually am getting the the single quote string,double quoted strings dynamically and also am using urljoin(dublequote,singlequote) so here i facing problem the output is combination both ... Thank u very much – Kumar Dec 15 '09 at 12:32
  • Thanks for answering the question instead of going into great detail about how python interprets quotes. I had a use case where a file needed its double quotes replaced with single quotes so that it could be passed into another language that was sensitive to the quote type. – Adam Hughes Oct 21 '15 at 17:01
1

Actually, none of the answers above as far as I know answers the question, the question how to convert a single quoted string to a double quoted one, regardless if for python is interchangeable one can be using Python to autogenerate code where is not.

One example can be trying to generate a SQL statement where which quotes are used can be very important, and furthermore a simple replace between double quote and single quote may not be so simple (i.e., you may have double quotes enclosed in single quotes).

print('INSERT INTO xx.xx VALUES' + str(tuple(['a',"b'c",'dfg'])) +';')

Which returns:

INSERT INTO xx.xx VALUES('a', "b'c", 'dfg');

At the moment I do not have a clear answer for this particular question but I thought worth pointing out in case someone knows. (Will come back if I figure it out though)

Bruno Castro
  • 21
  • 3
0

If you're talking about converting quotes inside a string, One thing you could do is replace single quotes with double quotes in the resulting string and use that. Something like this:

def toDouble(stmt):
    return stmt.replace("'",'"')
Mujtaba Ali
  • 1