Problems with a few "for" statements

[khskenny]

Have an issue with some for statements.

I must be missing somew logic here. I'm trying to get this compound interest program going. I can get it to go through 10 years on one interest rate, but when I throw in the second for statement to try to get that same output, but for varying interest rates it does not do as planned. In fact I somehow get 11%

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

int main()
{
   double amount;             
   double principal = 1000.0; 
   double rate = .05;         
   int year;                 

	for ( rate = .05; rate <= .10; rate += .01 ) {

		printf( "%4s%21s\n", "Year", "Amount on deposit" );

			for ( year = 1; year <= 10; year++ ) {
				
					amount = principal * pow( 1.0 + rate, year );

					printf( "%4d%21.2f\n", year, amount );  
						
		}
	}
   return 0; 

}

[dwks]

You shouldn't use floating point numbers for for loops if you can help it; due to floating point inaccuracies, the loop might not run the number of times you think it will.

The problem with your program is that you don't initialize principal before the second for loop.

[edit] You'll want something along these lines:

for ( year = 1, principal = 1000.0; year <= 10; year++ ) {

[/edit]

[swoopy]

> for ( rate = .05; rate <= .10; rate += .01 ); {
Maybe because you've got an extra semicolon in there?

[khskenny]

Hrmm, since I am not using any floats for year or rate, it should be ok right?

Also, is principal not initialized at the top @ 1000?

[khskenny]

> for ( rate = .05; rate <= .10; rate += .01 ); {
Maybe because you've got an extra semicolon in there?

HAH!

[swoopy]

However 1110 after one year at 5% interest doesn't seem quite right.

[khskenny]

However 1110 after one year at 5% interest doesn't seem quite right.

When I ran it sans extra semi colon, it did what I wanted, just not formated in an appealing or logical pattern, which I will fix. It does seem to do the interest sets as it should...

[swoopy]

Nevermind, rate was getting incremented to its final value by the first for-loop

[khskenny]

Thanks for the help guys. Bummer it was a careless error this time, but it got fixed. This forum ftw!

[swoopy]

When I ran it sans extra semi colon, it did what I wanted, just not formated in an appealing or logical pattern, which I will fix. It does seem to do the interest sets as it should...

After further observation, I've come to the same conclusion.