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Addition without the plus operator
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| // | |
| // Addition without `+` operator | |
| // | |
| func sum(n1: Int, n2: Int) -> Int { | |
| let result = n1 ^ n2 | |
| let carry = (n1 & n2) << 1 | |
| if carry != 0 { | |
| return sum(result, n2: carry) | |
| } | |
| return result | |
| } | |
| let r = sum(7, n2: 1) | |
| /* | |
| Step by step: | |
| '^' | |
| 00111 = 7 | |
| 00001 = 1 | |
| ----- | |
| 00110 = 6 | |
| '&' | |
| 00111 = 7 | |
| 00001 = 1 | |
| ----- | |
| 00001 = 1 | |
| '<< 1' | |
| 00010 = 2 | |
| === sum(6, n2: 2) === | |
| '^' | |
| 00110 = 6 | |
| 00010 = 2 | |
| ----- | |
| 00100 = 4 | |
| '&' | |
| 00110 = 6 | |
| 00010 = 2 | |
| ----- | |
| 00010 = 2 | |
| '<<' 1 | |
| 00100 = 4 | |
| === sum(4, n2: 4) === | |
| '^' | |
| 00100 = 4 | |
| 00100 = 4 | |
| ----- | |
| 00000 = 0 | |
| '&' | |
| 00100 = 4 | |
| 00100 = 4 | |
| ----- | |
| 00100 = 4 | |
| '<<' 1 | |
| 01000 = 8 | |
| === sum(0, n2: 8) === | |
| '^' | |
| 00000 = 0 | |
| 01000 = 8 | |
| ----- | |
| 01000 = 8 | |
| '&' | |
| 00000 = 0 | |
| 01000 = 8 | |
| ----- | |
| 00000 = 0 | |
| '<<' 1 | |
| 00000 = 0 | |
| === sum(8, n2: 0) === | |
| Result = 8 | |
| */ |
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