63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
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// lambda0.cpp -- using lambda expressions
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#include <iostream>
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#include <vector>
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#include <algorithm>
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#include <cmath>
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#include <ctime>
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const long Size1 = 39L;
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const long Size2 = 100*Size1;
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const long Size3 = 100*Size2;
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bool f3(int x) {return x % 3 == 0;}
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bool f13(int x) {return x % 13 == 0;}
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int main()
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{
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using std::cout;
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std::vector<int> numbers(Size1);
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std::srand(std::time(0));
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std::generate(numbers.begin(), numbers.end(), std::rand);
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// using function pointers
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cout << "Sample size = " << Size1 << '\n';
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int count3 = std::count_if(numbers.begin(), numbers.end(), f3);
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cout << "Count of numbers divisible by 3: " << count3 << '\n';
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int count13 = std::count_if(numbers.begin(), numbers.end(), f13);
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cout << "Count of numbers divisible by 13: " << count13 << "\n\n";
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// increase number of numbers
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numbers.resize(Size2);
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std::generate(numbers.begin(), numbers.end(), std::rand);
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cout << "Sample size = " << Size2 << '\n';
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// using a functor
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class f_mod
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{
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private:
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int dv;
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public:
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f_mod(int d = 1) : dv(d) {}
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bool operator()(int x) {return x % dv == 0;}
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};
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count3 = std::count_if(numbers.begin(), numbers.end(), f_mod(3));
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cout << "Count of numbers divisible by 3: " << count3 << '\n';
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count13 = std::count_if(numbers.begin(), numbers.end(), f_mod(13));
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cout << "Count of numbers divisible by 13: " << count13 << "\n\n";
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// increase number of numbers again
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numbers.resize(Size3);
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std::generate(numbers.begin(), numbers.end(), std::rand);
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cout << "Sample size = " << Size3 << '\n';
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// using lambdas
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count3 = std::count_if(numbers.begin(), numbers.end(),
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[](int x){return x % 3 == 0;});
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cout << "Count of numbers divisible by 3: " << count3 << '\n';
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count13 = std::count_if(numbers.begin(), numbers.end(),
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[](int x){return x % 13 == 0;});
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cout << "Count of numbers divisible by 13: " << count13 << '\n';
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// std::cin.get();
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return 0;
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}
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