Created
June 6, 2018 01:01
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Simple optional chaining
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| #include <cstring> | |
| #include <optional> | |
| using namespace std; | |
| const int A = 4; | |
| const int B = 6; | |
| const int CD = 8; | |
| const int E = 6; | |
| optional<int> fa(int a) | |
| { | |
| if (a >= A) { | |
| return a/2; | |
| } else { | |
| return nullopt; | |
| } | |
| } | |
| optional<int> fb(int b) | |
| { | |
| if (b >= B) { | |
| return b/3; | |
| } else { | |
| return nullopt; | |
| } | |
| } | |
| optional<int> fcd(int c, int d) | |
| { | |
| if (c*d >= CD) { | |
| return c*d/2; | |
| } else { | |
| return nullopt; | |
| } | |
| } | |
| optional<int> fe(int e) | |
| { | |
| if (e >= E) { | |
| return e; | |
| } else { | |
| return nullopt; | |
| } | |
| } | |
| int main(int argc, char *argv[]) | |
| { | |
| int a = atoi(argv[1]); | |
| int b = atoi(argv[2]); | |
| if (optional<int> tmp, x; | |
| (tmp = fa(a)) && (x = fb(b)) && (x = fcd(*tmp, *x)) && (x = fe(*x))) | |
| { | |
| return *x; | |
| } else { | |
| return 0; | |
| } | |
| } |
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