計算利率

Question

所以我想學習C++的大學課程，我必須寫一個使用這個公式的程序：

Amount = Principal * (1 + Rate/T)^T 

其中主要是儲蓄的平衡，利率是利率， t是一年內利息的複合次數。根據這本書，如果你輸入4.25作爲利率，12作爲與本金複合的次數1000.00，那麼你應該得到43.34利息，總金額應該是1043.34。我不確定我是否編碼錯了，但我想知道是否有人可以幫我解決我可能犯的錯誤！我試圖自己做一兩天，但我沒有運氣。

#include <iostream> 
#include <iomanip> 
#include <cmath> 

using namespace std; 

int main() 
{ 
    double PRINCIPAL; 
    double INTEREST_RATE; 
    double COMPOUND_AMOUNT; 


    cout << "What is your savings account balance?: " << endl; 
    cin >> PRINCIPAL; 
    cout << "What is your annual interest rate?: " << endl; 
    cin >> INTEREST_RATE; 
    cout << "How many times has your interest been compounded?: " << endl; 
    cin >> COMPOUND_AMOUNT; 

    double amt1 = 1 + (INTEREST_RATE/COMPOUND_AMOUNT); 
    double AMOUNT = PRINCIPAL * pow(amt1, COMPOUND_AMOUNT); 

    cout << "Interest Rate: " << INTEREST_RATE << endl; 
    cout << "Times Compounded: " << COMPOUND_AMOUNT << endl; 
    cout << "Principal: " << PRINCIPAL << endl; 
    cout << "Interest: " << INTEREST_RATE * COMPOUND_AMOUNT << endl; 
    cout << "Amount: " << AMOUNT << endl; 

    system("pause"); 
    return 0; 
} 

Answer 1

這是一個數學錯誤。如果您要將利率作爲「4.25％」，則需要將利率除以100.下面的代碼給出的數額爲1043.34，當輸入4.25作爲利率時。

#include <iostream> 
#include <iomanip> 
#include <cmath> 

using namespace std; 

int main() 
{ 
    double PRINCIPAL; 
    double INTEREST_RATE; 
    double COMPOUND_AMOUNT; 


    cout << "What is your savings account balance?: " << endl; 
    cin >> PRINCIPAL; 
    cout << "What is your annual interest rate? (in %): " << endl; 
    cin >> INTEREST_RATE; 
    INTEREST_RATE /= 100; 
    cout << "How many times has your interest been compounded?: " << endl; 
    cin >> COMPOUND_AMOUNT; 

    double amt1 = 1 + (INTEREST_RATE/COMPOUND_AMOUNT); 
    double AMOUNT = PRINCIPAL * pow(amt1, COMPOUND_AMOUNT); 

    cout << "Interest Rate (%): " << INTEREST_RATE * 100 << endl; 
    cout << "Times Compounded: " << COMPOUND_AMOUNT << endl; 
    cout << "Principal ($): " << PRINCIPAL << endl; 
    cout << "Interest ($): " << AMOUNT - PRINCIPAL << endl; 
    cout << "Amount ($): " << AMOUNT << endl; 

    system("pause"); 
    return 0; 
} 

感興趣的是，您的書正在談論美元的利息金額，即AMOUNT - PRINCIPAL。