Lab 2-3: 正實數乘法 (20%)

  • 輸入：兩正實數的整數部分、正實數的小數部分（輸入數字乘以\( \frac{1}{10,000,000,000} \)），正實數的小數部分不超過 10 位數。
  • 輸出：兩正實數數值、兩正實數的積，並且以 double 形式搭配 std::setprecision(15) 輸出。
  • 檔名：lab2_3_<學號>.cpp (e.g. lab2_3_106062802.cpp)

程式需提示使用者輸入兩正實數的整數部分、正實數的小數部分，程式需輸出兩正實數數值、兩正實數的積。

Format

Input real number (a), before decimal point: <(a) before decimal point>⏎
Input real number (a), after decimal point: <(a) after decimal point>⏎
The real number (a) is: <real number (a)>
Input real number (b), before decimal point: <(b) before decimal point>⏎
Input real number (b), after decimal point: <(b) after decimal point>⏎
The real number (b) is: <real number (b)>
(a) * (b) = <real number (a) * (b)>

Example

$ ./a.out
Input real number (a), before decimal point: 1⏎
Input real number (a), after decimal point: 2000000000⏎
The real number (a) is: 1.2
Input real number (b), before decimal point: 12⏎
Input real number (b), after decimal point: 3000000000⏎
The real number (b) is: 12.3
(a) * (b) = 14.76

$ ./a.out
Input real number (a), before decimal point: 1⏎
Input real number (a), after decimal point: 2000000000⏎
The real number (a) is: 1.2
Input real number (b), before decimal point: 12⏎
Input real number (b), after decimal point: 3⏎
The real number (b) is: 12.0000000003
(a) * (b) = 14.40000000036

Reference Code:

Credit: 金昆樂 (110021111)

#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
    double a1, a2, b1, b2;
    cout << "Input real number (a), before decimal point: ";
    cin >> a1;
    cout << "Input real number (a), after decimal point: ";
    cin >> a2;
    cout << "The real number (a) is: " << setprecision(15)
         << a1 + a2 / 10000000000 << endl;
    cout << "Input real number (b), before decimal point: ";
    cin >> b1;
    cout << "Input real number (b), after decimal point: ";
    cin >> b2;
    cout << "The real number (b) is: " << setprecision(15)
         << b1 + b2 / 10000000000 << endl;
    long double c = (a1 + a2 / 10000000000) * (b1 + b2 / 10000000000);
    cout << "(a) * (b) = " << setprecision(15) << c << endl;
    return 0;
}