// This is non-explicit-one-argument ctor.

// 意思是，只要一个实参即可，两个也行.

// explicit Fraction(int num, int den = 1) : numerator_(num),

// denominator_(den) {}

// explicit-one-agument ctor.

// 声明不能隐式地将其他类型转换到该类型.

explicit Fraction(const int num, const int den = 1)

: numerator_(num), denominator_(den) {}

operator double() const {

return static_cast<double>(numerator_) / denominator_;

}

operator int() const {

return static_cast<int>(numerator_ / denominator_);

}

Fraction operator+(const Fraction &f) {

return Fraction(this->num() + f.num(), this->den() + f.den());

}

int num() const { return numerator_; }

int den() const { return denominator_; }

int numerator_; // fraction

int denominator_; //

// Expect two strings not to be equal.

EXPECT_STRNE("hello", "world");

// Expect equality.

EXPECT_EQ(7 * 6, 42);

Fraction f1{3, 5};

Fraction f2{4};

int d = f1 + f2;

EXPECT_EQ(d, 1);

}