char str[100]; sprintf(str, "%f, %f\n%f, %f\n", mat[0], mat[1], mat[2], mat[3]);
// #include <sstream>が必要 std::ostringstream oss; oss << mat[0] << ", " << mat[1] << std::endl << mat[2] << ", " << mat[3] << std::endl; std::string str = oss.str();
#include <sstream> class Matrix2x2 { public: std::string GetPrintString() const; }; std::string Matrix2x2::GetPrintString() const { std::ostringstream oss; oss << mat[0] << ", " << mat[1] << std::endl; oss << mat[2] << ", " << mat[3] << std::endl; oss << std::endl; return oss.str(); } #include <fstream> int main() { Matrix2x2 mat(1.0, 2.0, 3.0, 4.0); std::cout << mat.GetPrintString() << std::endl; std::ofstream ofs("test.txt"); // ファイルへの出力 ofs << mat.GetPrintString() << std::endl; }