need help with simple Visual c++ prog

[piski]

I need to write a program that identifies the number of trailing zeroes in a number

ex. 1000 has 3 trailing zeroes and 1020 has 1 trailing zero..

I decided to set the limit between 1 and 100000. the only thing that I could think of is setting up a set of nested if statements like so

if (number < 100)
{
if (number%10 == 0)
cout << "the number has one trailing zero" <<endl;

the only thing is this can become quite repetetive as i am repeating the same steps for higher numbers..does anyone have any advice? i would greatly appreciate it
K

 

[DaveSimmons]

Think about making the number into a string and looking for '0' not 0.

 

[AgentEL]

use a while loop and decrement the "number" by dividing by 10

 

[DaveSimmons]

Originally posted by: AgentEL
use a while loop and decrement the "number" by dividing by 10

was just going to suggest this as method 2, though it assumes you know what (n % 10) does.

 

[piski]

1st..I dont understand how decrementing the number by 10 will help to find the number of zeroes at the end..

i see like 10/10 = 1 and but like 100/10 = 10. where does it tell you the number of zeroes there..sorry for being dumb..

2nd. would the while loop be like this?
while (number != 1)
{
statement
}??

thanks in advance
K

 

[AgentEL]

Originally posted by: piski
1st..I dont understand how decrementing the number by 10 will help to find the number of zeroes at the end..

i see like 10/10 = 1 and but like 100/10 = 10. where does it tell you the number of zeroes there..sorry for being dumb..

2nd. would the while loop be like this?
while (number != 1)
{
statement
}??

thanks in advance
K

hehe well, without giving away the entire thing:

Say you are given the number 132,000.

Your if statement is correct.

if (132,000 % 10 == 0) // you return true
you have a zero at the end

in the next iteration of the while loop, you want to check:

if (13,200 % 10 ==0)
you have another zero at the end

repeat, until the while loop fails ;-)

 

[DaveSimmons]

^ if you use this be sure you understand what "%" is and how it works here, in case you're asked to explain your work. Besides, "%" is a handy operator to understand for future use.

 

[Zombie]

or convert to string and check the characters, should be easy if you are allowed MFC.

 

[piski]

Alright well this is what I did
int j, zeroCount;
cout << "Enter another number: ";
cin >> j

while (j >= 1)
{
if (j%10 == 0)
{
zeroCount++
j = j/10
}
else
cout << "There are no trailing zeroes";



and of course its not working

 

[AgentEL]

looks close, but not quite.

You still want to run: j = j/10 even if the if condition fails.

and i'm assuming you left out a bunch of braces and semicolons out for brevity?

 

[piski]

why would i want to run it even if the condition fails?

 

[AgentEL]

your while condition j >= 1 depends on that j variable. If the number ends with a non-zero, it will fail the if condition, go to the else, print out the cout line and the j stays the same.

you will get an infinite loop.

 

[DaveSimmons]

Also think about zerocount, what value does it have before the while?

You're on the right track, working through the logic and finding your bugs is how you'll learn to do something like this without help next time.

Hopefully no one will step in and fix it for you, since you really do need to learn to fix and finish it yourself.

 

[piski]

yeah i know. but thanks for your help

 

[AgentEL]

best way to code this up is pick a number first and run it through your program. just do it on paper. don't even bother compiling/running anything.

a lot of the questions you have will be solved this way.

 

[DaveSimmons]

running through the code on paper or even in the debugger (stepping one line at a time) could help -- if you'd done that you'd see why you always need to have j = j/10 .

Edit: great minds think alike

 

[AgentEL]

Originally posted by: DaveSimmons
running through the code on paper or even in the debugger (stepping one line at a time) could help -- if you'd done that you'd see why you always need to have j = j/10 .

haha i like the way you think

 

[piski]

can someone tell me why i am getting an infinite loop out of this?
while (answer != 'Y' ||answer != 'N')
{
cout << "you have entered the wrong letter. please reenter: ";
cin >> answer;
}

 

[piski]

nevermind. got it!