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I have one more problem:
I need to displey number of prime numbers. Number is enetered from user.
I need to use only while loops.
I tried, but having problems-infinite loop
ThanksCode:
#include <stdio.h>
int main()
{
int n,i=1,prime=1;
printf("How many prime numbers do you want: ");
scanf("%d",&n);
while(n)
{
i=1;
while(i<=prime)
{
if(prime%i==0)
break;
i++;
}
if(prime==i)
{
printf(" %d",prime);
n--;
}
prime++;
}
return 0;
}
You need to start i at 2 not 1. All integers numbers are divisible by 1 so the case of (prime %i ==0) will always be true.
Thanks!
I really cannot believe I didn't see this.
Code:#include <stdio.h>
int main()
{
int n,i=1,prime=1;
printf("How many prime numbers do you want: ");
scanf("%d",&n);
while(n)
{
while(i<=prime)
{
if(prime%i==0)
{
break;
}
i++;
}
if(prime==i)
{
printf(" %d",prime);
n--;
}
prime++;
i=2;
}
return 0;
}
You should initalize i to 2 during declaration also.
Well, in that case it will not be displayed 1
1 is not a prime number. The first prime is 2.
First look up the definition of Prime number ;) . It says a prime number is one which is divisible by one and the number itself.It also must not be divisible by any other number. So 1 wont be a prime. 2 will be a prime ;).
Well by the definiton you provided, 1 is divisible by 1 and itself and isn't divisible by any other number, so it would be a prime. It's classed as a special case (i.e. "Well there's no real reason why and it's difficult to express so we'll just do it to be awkward"), isn't it? :confused:
1 is excluded from the definition. Here is my backup.Quote:
A prime number (or prime integer, often simply called a "prime" for short) is a positive integer p > 1 that has no positive integer divisors other than 1 and p itself.
Math World
Or, if you're too lazy to read linuxdude's link, here.
Quote:
More concisely, a prime number p is a positive integer having exactly one positive divisor other than 1. (emphasis added)
I can't believe all these replies about such minor issue as is 1 prime number or not.
Anyway my homework was to print 1,2,..etc. So I was supposed to write program that will print 1 and others. Thanks for help.
I would like to see similar discussion on my dijkstra algorithm problem but...
>I can't believe all this threads about such minor issue as is 1 prime number or not.
And you've been hanging around here long enough to have over 100 posts?
>So I was supposed to write program that will print 1 and others.
Code:printf("%d ", 1);
print_primes();
Unfortunetly, in some cases, this community is very helpful and we thrive on helping each other in what ways we can. even when ppl are just trying to get us to do their homework. :rolleyes: some of us will attempt the solution to a problem simply to satisfy our intellectual curiousity.Quote:
Originally Posted by Micko
Code:#include <stdio.h>
int main()
{
int n,i=1,prime=1;
printf("How many prime numbers do you want: ");
scanf("%d",&n);
/*always check scanf's return value. this case check to make sure n > 0 and is
an integer. type a letter when first run this program to see why */
while(n)
/*as long as n is not zero the code will run so unless user enters
'0' code will run accordingly better to put while ( (n > 1) ),theoretically;
but you already cause an infinite with the next statement */
{
i=1;
/*already declared i as 1 why declared again?
this will make sure i is ALWAYS 1 */
while(i<=prime)
/* prime is declared as 1 so saying while 1 is <= 1 */
{
if(prime%i==0){/* if the remainder of 1 / 1 == 0 break; this is true as there
is no remainder it evaluates to 0*/
printf("\nprime is now %d, i is now %d: ", prime, i);
printf("Press [enter] to continue your code: ");
getchar();
/*this is a test statement. it'll show you the program state. take it out for
poop and giggles */
break;
/* a break statement in a loop causes the program to break of that loop that
encloses it and go to the next stage of the program. In this case if prime == i print
prime */
}
i++;
/* this doesn't matter anyway cause you put i back to 1 again */
}
if(prime==i)
{
printf("%d\n",prime);
/* this will only print once and n will only decrease once
another infinite loop :d you need to read up on loops and rememebr when in doubt
paretheses */
n--;
}
prime++;/*prime will always increase but i won't because: you have this statement : */
i=2;
/* why even have this assignement cause you declare it back to 1 after so i
will forever be 1*/
}
printf("\nfinished doing what u told me.\nnotice anything strange?\n");
system("pause");
return 0;
}
>some of us will attempt the solution to a problem simply to satisfy our intellectual curiousity.
But those of us that could help the most by posting a complete solution to homework satisfy our "intellectual curiosity" and don't post it. ;) Doing someone else's homework does more harm than good.
><snip code>
Tabs and spaces don't mix well. It's usually better if you only use spaces and format your comments and mix them with code to be easier to read. As it is I find your program uncomfortable.
I don't think I solved it. I was merely showing the individual a way to think in order to come to a satisfactory conclusion. or the expected results.Quote:
Originally Posted by Prelude
don't be afraid of the code, it won't touch you inapropiately or anything. ;) actaully i was trying to find the vb code tags to format it better, but i couldn't.Quote:
><snip code>
Tabs and spaces don't mix well. It's usually better if you only use spaces and format your comments and mix them with code to be easier to read. As it is I find your program uncomfortable.
In anycase the issue is that this individual needs help on how to go about getting the desired solution. If s/he pastes the code and run it - which they will have to do - the code will not only be easier to read but s/he can also check the program state, which is more important.
>If s/he pastes the code and run it - which they will have to do - the code will not only be easier to read
It's still poorly formatted when I cut and paste into my text editor. ;)
u suck!!Quote:
Originally Posted by Prelude
:p
Occasionally. :pQuote:
Originally Posted by caroundw5h
Listen , my intention was not to underestimate anyone's work.
Like I said I have solved my problem and post code. If 1 is really prime number or not is arguable. For someone it is and for someone it is not. However I never past my homework and ask you to do it. I paste code only and only if I did't manage to do it myself or didn't have time to bother. n*pair (n integer) of eyes can see some that I can't at the moment.
I find this board very usefull and didn't want to disprage anyone, but I am surprise with the fact that all this discussion about number 1. Anyway I would left it to mathematicians to agree.
Cheers!!!!!!!!
don't think too highly about this. no one is disparaging anyone's work. We critique and give constructive suggestions and we learn from each others work. if an individual doesn't, they stagnate.
as to whether 1 is a prime number or not. read linuxdude's post. if you can't listen, you prlly can't learn either.
>but I am surprise with the fact that all this discussion about number 1
We're a community of pedants. Those that aren't tend not to stick around for long periods of time. :)
>For someone it is
Anyone who believes the mathematical definition of a prime number.
>and for someone it is not
Anyone who doesn't. ;)
:) :) :)
Whoa! Please tell me that has another meaning than the one my sick mind gave it...Quote:
Originally Posted by Prelude
X^2 is a perv, wait I had the same thought. Hmm But I'm exempt from that status :)
Micko: There are a lot of things you'll be asked, as a programming student, to do that aren't "correct." Do them, get the grade, realize your instructor is wrong, and move on :)
Better yet:Quote:
Originally Posted by Thantos
1) Do them.
2) Add comment blocks that quote things like the standard, and the like, proving they're wrong.
I'm sure they'd appreciate the constructive criticism. ;)Code:int main( void )
{
char buf[80] = {0};
printf("Enter a line: ");
/* Get a line from the user:
* NOTE: One should NEVER use gets, because it is horribly
* unsafe, and prone to buffer overflows. But, since I'm left
* with no other choice, I will be forced to use it. However,
* be aware that if you crash this program when testing it for
* my grade, it's your own fault, since I'd use fgets, but you
* won't let me.
*/
gets( buf );
return 0;
}
Quzah.
Heh I actually told my instructor that I did not have the ability to type "void main()" and that my fingers would instead type "int main()".
better yetCode:int main(void)
Yes of course :)
Oh and adding a copyright notice to the top of the code is always fun also. I also thought (but didn't) about using winzip's password feature on my files.
What really sucked was having to put a comment on every closing }. Most of them were nothing more than /* End of if statement */ and the like :)
Quote:
Originally Posted by Thantos
Do them, get the grade, realize your instructor is wrong, and move on
Better yet:
1) Do them.
2) Add comment blocks that quote things like the standard, and the like, proving they're wrong.
Code:
Well I have had many "so called experts"- in both my C and Java classes in the past. I usually tell my students if they want to challenge me about various coding issues- prove their answer in writing and cite were they found their sources. Then and only then I will consider changing anything.Quote:
int main( void )
{
char buf[80] = {0};
printf("Enter a line: ");
/* Get a line from the user:
* NOTE: One should NEVER use gets, because it is horribly
* unsafe, and prone to buffer overflows. But, since I'm left
* with no other choice, I will be forced to use it. However,
* be aware that if you crash this program when testing it for
* my grade, it's your own fault, since I'd use fgets, but you
* won't let me.
*/
gets( buf );
return 0;
}
I'm sure they'd appreciate the constructive criticism.
Quzah.
I usually find in most cases students:
1. cant back up their claims
2. can't follow directions on a given assignment
3. love to "whine" about their grades :rolleyes:
I am sure glad I don't have some of you in my programming classes!!! :D
Quzah, have you ever thought about teaching?? :)
And there are plenty of "so called experts" teaching. In classes where there is wiggle room for what is "right" and what is "wrong" I prefer to figure out what the instructor wants and give them that even if I don't agree with it. Heck half of my answers for my tutor training class were nothing more then lip service. I wasn't about to go "I think this idea is a crock." Same applies to my programming classes. If the instructor wants a global variable then I'll use the global variable. I'm still going to use the best techniques I know in my personal projects but I want the dang A :)
Number 2 is the truth. But you also have to add in: Can only follow step by step instructions and only if given in the smallest steps.
We had one assignment which was to randomily place queens on a 4x4 chessboard until there were no open safe spots left. He wrote out the method out on the board and gave the simplist method to use. I still had people coming in for tutoring that needed hand holding to figure out what to do.
Thanos,Quote:
And there are plenty of "so called experts" teaching. In classes where there is wiggle room for what is "right" and what is "wrong" I prefer to figure out what the instructor wants and give them that even if I don't agree with it. Heck half of my answers for my tutor training class were nothing more then lip service. I wasn't about to go "I think this idea is a crock." Same applies to my programming classes. If the instructor wants a global variable then I'll use the global variable. I'm still going to use the best techniques I know in my personal projects but I want the dang A
You are right here. I am not a so called expert-by no means- but I mean by " cant back up their claims" when I know the students are obviously wrong- and the like to make it known to the entire class "of their expertise".
You are following directions-your grade "A"
Not hard is it.
You would not believe how many people in ours MS Applications classes that can't READ the steps , when it is spelled out in the text. As you mentioned- they want that "hand holding". :(Quote:
We had one assignment which was to randomily place queens on a 4x4 chessboard until there were no open safe spots left. He wrote out the method out on the board and gave the simplist method to use. I still had people coming in for tutoring that needed hand holding to figure out what to do.