Simple Interest Calculator in C

Program Explanation

This program calculates the simple interest based on the principal amount, the rate of interest, and the time period.
The formula used to calculate simple interest is:

    Simple Interest (SI) = (Principal * Rate * Time) / 100

The structure of the program is as follows:

1. Include necessary headers: The #include <stdio.h> directive is used to include the standard input-output library, which is necessary for using printf and scanf functions.
2. Function Declaration: The main function, int main(), is the entry point of the program.
3. Variable Declaration: Declare variables to store the principal amount, rate of interest, time period, and calculated simple interest.
4. User Input: Use scanf to take input from the user for the principal amount, rate of interest, and time period.
5. Calculation: Compute the simple interest using the given formula.
6. Output: Display the calculated simple interest using printf.
7. Return Statement: The return 0; statement signifies the end of the main function.

Program Code

#include <stdio.h>

/**
 * main - Entry point of the program
 *
 * This function calculates the simple interest based on user inputs
 * for the principal amount, rate of interest, and time period.
 *
 * Return: 0 on success
 */
int main() {
    // Variable declaration
    float principal, rate, time, simpleInterest;

    // Taking user input
    printf("Enter the principal amount: ");
    scanf("%f", &principal);

    printf("Enter the rate of interest: ");
    scanf("%f", &rate);

    printf("Enter the time period in years: ");
    scanf("%f", &time);

    // Calculating simple interest
    simpleInterest = (principal * rate * time) / 100;

    // Displaying the result
    printf("The simple interest is: %.2f\n", simpleInterest);

    // Return statement
    return 0;
}

Documentation

The program includes documentation comments to explain its structure and functionality:

• Header Inclusion:

  #include <stdio.h>

  This line includes the standard input-output library necessary for input and output operations.

• Main Function:

  
  /**
   * main - Entry point of the program
   *
   * This function calculates the simple interest based on user inputs
   * for the principal amount, rate of interest, and time period.
   *
   * Return: 0 on success
   */
          

  The main function is the entry point of the program where execution starts.

• Variable Declaration:

  float principal, rate, time, simpleInterest;

  Declares four variables to store the principal amount, rate of interest, time period, and calculated simple interest.

• User Input:

  
  printf("Enter the principal amount: ");
  scanf("%f", &principal);
  
  printf("Enter the rate of interest: ");
  scanf("%f", &rate);
  
  printf("Enter the time period in years: ");
  scanf("%f", &time);
          

  Prompts the user to enter the principal amount, rate of interest, and time period. The inputs are stored in the respective variables.

• Calculation:

  simpleInterest = (principal * rate * time) / 100;

  Calculates the simple interest using the provided formula.

• Output:

  printf("The simple interest is: %.2f\n", simpleInterest);

  Displays the calculated simple interest.

• Return Statement:

  return 0;

  Indicates the end of the main function and returns 0 to the operating system.