Hi, I've founded this three methods with my friend (foundef by ourself, not on internet but I think that they already exist).
The first and second metods are for numeric variables: it consists to merge the variable and next extracts it:
First:
A = 5;
B = 3;
A = A+B; //5+3=8
B = AB; //83 = 5
A = AB; //85 = 3
Second:
A = 6;
B = 9;
A = AB; //69=3
B = A+B; //3+9=6
A = BA; //6(3) =9
The third method is my favourite: it consist to merge it with the exclusive sum/exclusive or (XOR bit to bit)
/*
This is the XOR table: it is true when only one is true (or when the two bits are different)
x  y  x^y (In C/C++, ^ is XOR bit to bit)
0  0  0
0  1  1
1  0  1
1  1  0
*/
A=255; //11111111
B=134; //10000110
A=A^B; //01111001
/*
11111111 ^
10000110 =
01111001
*/
B = A^B; //11111111 (255)
/*
01111001 ^
10000110 =
11111111
*/
A = A^B; //10000110 (134)
/*
01111001 ^
11111111 =
10000110
*/
It's all
Swap without third variable (3 methods)

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 Posts: 93
 Joined: Thu Apr 17, 2014 10:10 am
Swap without third variable (3 methods)
I'm Italian but we can speak C++
Re: Swap without third variable (3 methods)
The three methods are similar (A^B = AB). And all of they are only valid for small int values. If you use big values, then A+B or AB may be out of range.
Anyhow, what's the (great) advantage from the usal tempvar method?
Anyhow, what's the (great) advantage from the usal tempvar method?
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