Notice that 25 is a square. Check that your loop condition accounts for this. Also, it may be more prudent to use ceil instead of round (EDIT: or just add 1), or use an algorithm that specifically computes the square root of integers instead of sqrt (due to floating point inaccuracy)Originally Posted by ImaCnoob
Last edited by laserlight; 10-08-2012 at 09:49 PM.
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sign changed from > to <
Notice that 25 is a square
Are you looping through the for loop whileCode:i<sqrt(n) or i<=sqrt(n)
Fact - Beethoven wrote his first symphony in C
ok, i made those changes and here is the output:
8 = 2 x 4
8: NOT A PRIME Number
25 = 5 x 5
25: NOT A PRIME Number
101 = 1 x 101
101: PRIME Number
5001 = 3 x 1667
5001: NOT A PRIME Number
10213 = 7 x 1459
10213: NOT A PRIME Number
56777 = 7 x 8111
56777: NOT A PRIME Number
765321 = 3 x 255107
765321: NOT A PRIME Number
317971 = 1 x 317971
317971: PRIME Number
1028743 = 131 x 7853
1028743: NOT A PRIME Number
23498271 = 3 x 7832757
23498271 = 9 x 2610919
23498271: NOT A PRIME Number
987278023 = 149 x 6626027
987278023 = 761 x 1297343
987278023 = 8707 x 113389
987278023: NOT A PRIME Number
1768374681 = 3 x 589458227
1768374681 = 157 x 11263533
1768374681 = 471 x 3754511
1768374681: NOT A PRIME Number
It looks good to me, I have checked a few and everything is correct.
Thanks for the help everyone!!! Your speed and helpfulness without just giving me the code is why I use this forum!
Looks good to me - Good work
Fact - Beethoven wrote his first symphony in C
Could you explain what changes you made in order to make 25 show as a non-prime number?
this is in my code, the <= helped me
i forget if that was it or not, does it help?Code:for(i = Start; i <= Stop; i++)
Perfect! Works out great.
Now, I don't suppose you've done the second part of this, have you?
haha
I've done the simple part and displayed only the numbers that are prime without showing factors, but I'm having trouble scanning in a range of numbers - would an array be used here?
Edit: Never mind that. You can do this with a simple if loop and a counter.
Final edit: Got the second part to work. Let me know if you run into any trouble or want me to post my code.
Last edited by NextName; 10-08-2012 at 10:53 PM.
I cant figure out how to scan in the specified range, could you post some of the code for me?
I had to add this in after declaring the first variables:
Then changed the while loop to:Code:printf("Enter start of range: "); scanf("%d", &Range1); printf("Enter end of range: "); scanf("%d", &Range2);
Code:if (Range1 != Range2) { for(n = Range1; n <= Range2; n++)
should the n in your code be an i? I cannot get this to work
EDIT: nevermind, this somewhat works, I have it print out that all numbers in my range are prime. here is code:
Code:#include <stdio.h> #include <stdlib.h> #include <math.h> int main (void) { //declare variables int n, is_prime, Start, Stop, display_factor, i, Lower, Upper; printf("Enter lower range:"); scanf("%d", &Lower); printf("Enter upper range:"); scanf("%d", &Upper); //loops until it reaches the End Of File if (Lower != Upper) { is_prime = 1; for(n = Lower; n <= Upper; n++) { if ((n%i) == 0) { is_prime = 0; } else { printf("%d: PRIME Number\n\n", n); } } } return 0; }
Last edited by ImaCnoob; 10-08-2012 at 11:21 PM.
This board seems a bit messed up right now.
I think you changed up too much of your code. You trashed a lot of the stuff in your first for loop when you should have left it in. There is only supposed to be a minor change from the first part to the second, which is mostly just modifying that while loop call and getting rid of the options for when a number isn't prime.
