Question

Can someone help me write a retirement calculator program in c code. I want to write a program that the user can enter their age, amount they wish to save each month, the interest rate, and the age they wish to retire. I would like to use a switch loop, if else loop or do while loop. the output should show them how much they should have in a retirement savings account at the age they wish to retire at. This has to be in C code. Someone helped me with a good working code. but I don't think it was compounding to what I was looking for. I was looking to use a future sum equation like futureValue = savingAmt * pow(1 + intRate / periods, -1 / periods); Thank You in advance.

Answer 1

#include <stdio.h>
#include <math.h>
//This function returns total savings
//It takes current age, monthly deposit, rate and retirement age as arguments
double savingsAmount(int age, double monthly_amount, double yearly_rate, int retirement_age)
{
double amount = 0; //To store total savings
int years = retirement_age - age; //Total years
if(years <= 0) //invalid input
return 0;
//Use : futureValue = savingAmt * pow(1 + intRate / periods, -1 / periods)
//Assume compounding occurs quarterly, i.e every 4 months
int N = 4;
int t = years*12;
yearly_rate = yearly_rate/100.0; //Convert % to decimals
while(t)
{
amount += monthly_amount * pow((1 + yearly_rate/N), N*t/12.0) ;
t--;
}
return amount; //Final amount
}

int main(void) {
char ch = 'Y'; int age, retirement_age;
double monthly_amount, yearly_rate;   
do{
printf("Enter age : "); scanf("%d", &age);
printf("Enter monthly amount to deposit : "); scanf("%lf", &monthly_amount);
printf("Enter yearly_rate : "); scanf("%lf", &yearly_rate);
printf("Enter retirement_age : "); scanf("%d", &retirement_age);
//Call function
double ret_amount = savingsAmount(age,monthly_amount,yearly_rate,retirement_age);
printf("Total savings amount = %lf \n", ret_amount);
printf("Try again ? Y/N : "); scanf(" %c", &ch);
}while(ch=='Y' || ch=='y');
return 0;

}