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Rahul Parshi
Rahul Parshi

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Swapping 2 variables(numbers, characters, strings, booleans) without using extra variable

#firstpost #programming

Numbers

Using arithmetic operation 

 a = a + b; b = a - b; // (a+b) - (b) = a a = a - b; // (a+b) - (a) = b
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Using binary operation 

 a = a ^ b; b = a ^ b; // (a ^ b) ^ (b) = a ^ 0 = a a = a ^ b; // (a ^ b) ^ (a) = 0 ^ b = b
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Characters

If characters are stored with it's ASCII value like C++, same method as numbers can be used. Else characters can be type caste to numbers.

 a = (char) ((int)a ^ (int)b); b = (char) ((int)a ^ (int)b); a = (char) ((int)a ^ (int)b);
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Strings 

 a = a + b; b = a.substr(0, (a.length() - b.length())); a = a.substr(b.length(), a.length());
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Space complexity = S(M + N) where M is length of a and N is length of b;

Booleans

If both the variables are same, swapping is not required else need to toggle the values.

 if (a != b){ a = true ^ a; //toggles the value b = true ^ b; }
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Rahul Parshi •

In javascript, to swap 2 variables.

[a, b] = [b, a];
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