C program to calculate compound interest:

• The program first declares five variables: principal, rate, time, interest, and periods.
• It then prompts the user to enter the principal amount, rate of interest, time in years, and number of compounding periods per year using the printf() and scanf() functions.
• The formula for calculating compound interest is A = P(1 + r/n)^(nt) - P, where A is the amount, P is the principal, r is the rate of interest, n is the number of times interest is compounded per year, and t is the time in years. The program calculates the compound interest using this formula and stores it in the interest variable.
• Finally, the program prints the compound interest using the printf() function with a precision of two decimal places.
• Note that the pow() function from the math.h library is used to calculate the power of a number.

#include <stdio.h>
#include <math.h>

int main() {
    float principal, rate, time, interest;
    int periods;

    printf("Enter principal amount: ");
    scanf("%f", &principal);

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

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

    printf("Enter number of compounding periods per year: ");
    scanf("%d", &periods);

    interest = principal * pow((1 + (rate / periods)), (periods * time)) - principal;

    printf("Compound interest = %.2f", interest);

    return 0;
}

OUTPUT

Enter principal amount: 1000
Enter rate of interest: 5
Enter time in years: 2
Enter number of compounding periods per year: 12
Compound interest = 105.13