C++ Exercises: Calculate Compound Interest

Last update on August 11 2025 12:58:12 (UTC/GMT +8 hours)

Compound Interest Calculation

Write a C++ program to enter P, T, R and calculate compound interest.

Sample Solution:

C++ Code :

#include<iostream> // Including input-output stream header file
#include<math.h> // Including math functions header file

using namespace std; // Using the standard namespace

int main() { // Start of the main function

    float p, r, t, cp, ci; // Declaring variables to store principle, rate, time, compound interest, and compound amount

    cout << "\n\n Calculate the Compound Interest :\n"; // Displaying the purpose of the program
    cout << " -------------------------------------\n"; 

    cout << " Input the Principle: "; // Prompting the user to input the principle amount
    cin >> p; // Taking input of the principle amount from the user

    cout << " Input the Rate of Interest: "; // Prompting the user to input the rate of interest
    cin >> r; // Taking input of the rate of interest from the user

    cout << " Input the Time: "; // Prompting the user to input the time period
    cin >> t; // Taking input of the time period from the user

    ci = p * pow((1 + r / 100), t) - p; // Calculating the compound interest using the formula: P(1 + r/n)^nt - P
    cp = p * pow((1 + r / 100), t); // Calculating the compound amount

    cout << " The Interest after compounded for the amount " << p << " for " << t << " years @ " << r << " % is: " << ci; // Displaying the calculated compound interest
    cout << endl; // Displaying an empty line for better readability

    cout << " The total amount after compounded for the amount " << p << " for " << t << " years @ " << r << " % is: " << cp; // Displaying the calculated compound amount
    cout << endl; // Displaying an empty line for better readability

    cout << endl; // Displaying an empty line for better readability
    return 0; // Returning 0 to indicate successful program execution
}

Sample Output:

Calculate the Compound Interest :                                     
 -------------------------------------                                 
 Input the Principle: 20000                                            
 Input the Rate of Interest: 10                                        
 Input the Time: 1.5                                                   
 The Interest after compounded for the amount 20000 for 1.5 years @ 10 
% is: 3073.8                                                           
 The total amount after compounded for the amount 20000 for 1.5 years @
 10 % is: 23073.8

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to compute compound interest with monthly compounding and display both the interest and final amount.
Write a C++ program that calculates compound interest using a loop for iterative compounding and then compares it to simple interest.
Write a C++ program to calculate compound interest with user-selectable compounding frequency and format the output with precision.
Write a C++ program that computes compound interest and then prints a detailed breakdown of the balance after each compounding period.

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C++ Code Editor:

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