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46 lines
1.1 KiB
C++
46 lines
1.1 KiB
C++
// http://www.cplusplus.com/reference/numeric/accumulate/
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#include <cassert>
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#include <iostream>
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#include <functional> // std::minus
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#include <numeric> // std::accumulate
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int myfunction (int x, int y) { return x+2*y; }
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struct myclass {
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int operator()(int x, int y) const { return x+3*y; }
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} myobject;
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int main() {
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int init = 100;
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int numbers[] = {10, 20, 30};
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int res;
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std::cout << "using default accumulate: ";
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res = std::accumulate(numbers, numbers+3, init);
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std::cout << res;
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assert(res == 100+10+20+30);
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std::cout << '\n';
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std::cout << "using functional's minus: ";
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res = std::accumulate(numbers, numbers+3, init, std::minus<int>());
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std::cout << res;
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assert(res == 100-10-20-30);
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std::cout << '\n';
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std::cout << "using custom function: ";
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res = std::accumulate(numbers, numbers+3, init, myfunction);
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std::cout << res;
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assert(res == 100+20+40+60);
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std::cout << '\n';
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std::cout << "using custom object: ";
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res = std::accumulate(numbers, numbers+3, init, myobject);
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std::cout << res;
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assert(res == 100+30+60+90);
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std::cout << '\n';
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return 0;
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}
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