c - my simple intrest calculator is not working for some reason

Question

my simple intrest calculator that I create used c programming is not working for some reason. i want to bring me the answer but always returns zero and i literally don't know what should I do. I am kinda new to c and I really cannot figur it out

i would really appreciate if any of you could help me out. thanks

// Assignment - 1, Section - 2.
/** Please read the instructions in the comment and 
    write the code accordingly. 
    This assignment will test your understanding with console input and output.
    Just in case if you do not know the meaning of the term 'console', we typically
    indicate it to mean keyboard and terminal. Input console indicates to keyboard and 
    output console indicates terminal.
    This will also test your ability to use variables.
*/  
int main()
{
    // Please follow the instructions and write the code chronologically.
    //  1. Declare a double type variable named rate and assign 0.06 to it
double rate=0.06;


    //  2. Declare an integer variable, name it duration.

int duration;

    //  3. Declare a double variable and name it principal_amount

double principal_amount;

    //  4. Declare a double variable and name it total_interest
double total_interest;


    //  5. Prompt user to input duration in year. Read the year value in duration using 
    //     scanf. Since duration is integer you must use %d.

 printf("input duration in year");

scanf("%d", &duration);



    //  6. Prompt user to input principal amount of loan. Read the value in the 
    //     variable principal_amount. Think about the format specifier this time. 
    //     principal_amount is not an integer, it is a double, so use the format specifier
    //     of double.

printf("input the amount of loan:
");

scanf("%f", &principal_amount);

    //  7. Now you will calculate the total interest, if R is rate, D is duration and P 
    //     is principal then the total interest should be calculated as follows:
    //      I = (P * D * R)

int I= (rate*duration*principal_amount);
    printf("%d", I);
    //     Use the above formula to calculate the total interest and finally print the 
    //     amount into the console. Your output should be like the following: 
    //     Output: 
    //          Your total payable interest is $3000.000000  when principal_amount given as 1000.0, duration is 5                    
    //          



    return 0;

}```

question from:https://stackoverflow.com/questions/65923557/my-simple-intrest-calculator-is-not-working-for-some-reason

Answer 1

Use %lf format specifier for double and %d format specifier for int. This solves the issue and prints the required answer.

scanf("%lf", &principal_amount);

double I= (rate*duration*principal_amount);
printf("%lf", I);