Is it possible to swap two registers without using a third one?

Question

Anonymous · Accepted Answer

Add two variables and assign the value into First variable. Subtract the Second value with the result Value. and assign to Second variable. Subtract the Result of First Variable With Result of Second Variable and Assign to First Variable. Example:

int a=5,b=10;a=a+b; b=a-b; a=a-b;

Vikram · Answer

When we talk of registers XORing is the operation that we can perform.

Say a = 5 ; b = 10

a = a XOR b;    // 5 XOR 10 is 15 so "a = 15"
b = a XOR b     // 15 XOR 10 is 5 so "b = 5"
a = a XOR b     // 15 XOR 5 is 10 so "a = 10"

So in the end a = 10 and b = 5

HC · Answer

Using XOR is probably better than using addition as addition might cause overflow.

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