How to swap values of two string variables without a temp variable?

Question

For example, I have two string variables:

string a = " Hello ";
string b = " World ";

How can I swap it without a temporary variable?

I found an example, but it used a third variable for the length of a:

int len1 = a.Length;
a = a + b;
b = a.Substring(0, len1);
a = a.Substring(len1);

How can I do that?

UPD, suggested solution for decimal data type, in ma case i've asked about string data type.

I think you could use `Interlocked.Exchange` for that: https://msdn.microsoft.com/de-de/library/f2090ex9(v=vs.110).aspx — Nico, Sep 14 '16 at 19:29
Without any further information, I would say the best way is to avoid not using a third variable. There are many (horrible) ways of doing it, but appart from producing unreadable code, cannot see what will be the benefits — Thomas W., Sep 14 '16 at 19:31
@PavneetSingh It says in the question why he's not satisfied with that answer — Sam I am says Reinstate Monica, Sep 14 '16 at 19:32
@SamIam yeah man, i eyes are shutting down i didn't even looked at length,it's 1 am here :P ,length property could have been used dynalically , anyway nice answer buddy and great efforts guys. thumbs-up — Pavneet_Singh, Sep 14 '16 at 19:41
Possible duplicate of *[How do I swap two strings without using a temporary variable?](http://stackoverflow.com/questions/34818289/how-do-i-swap-two-strings-without-using-a-temporary-variable)* — Peter Mortensen, Sep 16 '16 at 03:54
@PeterMortensen i was look another resolve what I was find for my target, may be, you can flag it like a duplicate — Uladz Kha, Sep 16 '16 at 07:19
Does this answer your question? [Swap two variables without using a temporary variable](https://stackoverflow.com/questions/804706/swap-two-variables-without-using-a-temporary-variable) — victortv, Jan 22 '20 at 23:16
@victortv no, this solution for decimals, I need solution for strings — Uladz Kha, Jan 24 '20 at 07:54

Salah Akbari · Accepted Answer · 2016-09-15T08:56:15.573

3

You can use SubString without using a temp variable, like this:

string a = " Hello ";
string b = " World ";

a = a + b;//" Hello  World "
b = a.Substring(0, (a.Length - b.Length));//" Hello "
a = a.Substring(b.Length);//" World "

edited Sep 15 '16 at 08:56

answered Sep 14 '16 at 19:31

Salah Akbari

39,330
10
79
109

score 0 · Answer 2 · edited Sep 14 '16 at 22:21

0

Just use some other means of swapping.

string stringOne = "one";
string stringTwo = "two";

stringOne = stringOne + stringTwo;
stringTwo = stringOne.Substring(0, (stringOne.Length - stringTwo.Length));
stringOne = stringOne.Substring(stringTwo.Length);

// Prints stringOne: two stringTwo: one
Console.WriteLine("stringOne: {0} stringTwo: {1}", stringOne, stringTwo);

edited Sep 14 '16 at 22:21

astidham2003

966
1
11
33

answered Sep 14 '16 at 19:32

MikeB0317

1
1

4

I don't believe that will compile – Sam I am says Reinstate Monica Sep 14 '16 at 19:33

score 0 · Answer 3 · answered May 15 '18 at 21:47

0

   string str1 = "First";
        string str2 = "Second";
        str1 = (str2 = str1 + str2).Substring(str1.Length);
        str2 = str2.Substring(0,str1.Length-1);

answered May 15 '18 at 21:47

Ali Humayun

1,756
1
15
12

score 0 · Answer 4 · answered Jan 26 '23 at 21:14

I'm fond of doing it this way although underneath it's using resources to make it fully thread-safe, and I wouldn't be surprised if it was using a local variable behind the scenes.

string str1 = "First";
string str2 = "Second";
str2 = System.Interlocked.Exchange(ref str1, str2);

How to swap values of two string variables without a temp variable?

4 Answers4