[[練習問題/回答例]] **素数判定 [#rafca80c] #geshi(cpp){{ #include <iostream> #include <cmath> #include <sstream> using namespace std; int main( int argc, char** argv ){ int x; bool is_prime = true; if(argc < 2){ cout << "Input x > "; cin >> x; }else{ istringstream is(argv[1]); is >> x; } for( int i = 2; i < static_cast<int>(sqrt(x)) + 1; i++){ if(( x % i ) == 0 ){ is_prime = false; break; } } if( is_prime ) cout << x << "は素数" << endl; else cout << x << "は非素数" << endl; return 0; } }}