Random numbers to stay under 200

Hey guys Here is my code (it is a function as usual with my crap)

Code:

void fPlanes(FILE *Fplanes) { /*declaring arrays, I am going to use int to keep everything standard */ int aXaxis[50]; int aYaxis[50]; int aZaxis[50]; int q = 0; aXaxis[50] = (int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200; aYaxis[50] = (int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200; aZaxis[50] = (int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200; for(q=0; q < 50; q++) { fprintf(Fplanes, "%i %i %i \n", aXaxis[q], aYaxis[q], aZaxis[q]); } }

As you can see this creates a file with 3 columns of numbers, I am trying to get the numbers under 200 (or any number set that I want) that equation above is suppose to keep them above 0 and less then too but it does is keep the numbers under 200, and it can be way under like -18921341243, How do I make each of these arrays be between 0 and 200 or 1 and 200?

I know my syntax is right.

if it helps, Here is a copy of the text file:

-1878016948 0 0
1 66752 0
-1073744568 -1881138584 69644
-1878016840 -1073743728 61440
2 0 6
-1769496876 69284 20
0 -1073743716 1915905074
-1073743096 28 5
8 1919164426 -1881131436
1 28 -1073743456
-1073743092 2185 0
-1073743840 0 -1881131096
66512 69348 0
-1073743840 -1073743592 0
0 5 0
-1881053704 1 -1073743096
0 6 -1073743084
0 1684107892 -1073743092
0 1744833792 -1610583185
-1073743096 0 1819213832
8 1932 -1073743084
-1610604580 69644 -1073743092
-1610605624 -1881073184 -1610554928
69352 -1073743600 850045863
-1878391332 -1610549856 0
-1073743840 -1881072476 0
-1073743092 -1881119204 0
-1073743768 -1073743632 0
-1073743712 0 0
-268435456 -1769492588 0
0 23456 0
214748364 1818585441 1784767074
-858993460 5960 1627389952
0 -1879040756 0
23450 -1880805376 0
-1881094536 3146092 -1881053704
-1881009952 50352 75684
-1073743664 -1073743496 0
-1073743672 -1073743084 0
-1073743812 -1073743092 -1073743096
75756 -1880801884 8
1050560 1050560 69144
1051904 -1881129564 8
-1880805376 25697 -1073776273
-1881075004 1920231424 1684078600
1 75684 -1073743360
-1073743092 6 1
-1073743840 5 -1878966476
66512 20 69008
-1073743360 0 -1073743084

Quote:

Originally Posted by sloopy

Code:

aXaxis[50] = (int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200;

This line assigns to the fiftieth element of aXaxis (which is not even part of the array, since indices run from 0 to 49). Your for loop is printining out uninitialized values.

should I put a counter in?

As others have said, you need to loop through your indecies, and not try to do [50]. C & C++ arrays are zero-indexed, so they start at zero and go to length-1.

Quote:

Originally Posted by sloopy

Code:

(int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200;

That can be simplified, greatly, and look a lot less confusing. I see no point in (double)(1)... a simple 1.0 should suffice. You can also drop the parenthesis around RAND_MAX, they do nothing. Casting in pretty high in precedence, it'll happen before + - * /. Once you do that, you'll see you're casting it to an (int) before multiplying by 200, not what you wanted. So, after fixing that up:

Code:

(int) ((double) rand() / ((double) RAND_MAX + 1.0) * 200.0);

I don't think you need that final (int) either, since you're assigning it to an int, that cast should occur anyways.

Edit: Your formula in itself is broken. If rand() returns 0, you'll get zero, not what you want. I suggest multiplying by 199.0 (That's the number of numbers between 0 and 200, aka, the size of your range) and adding 1 (the offset of your range) to the final result.

Code:

1 + ((double) rand() / ((double) RAND_MAX + 1.0) * 199.0);

Quote:

Originally Posted by sloopy

aXaxis[50] = (int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200;
aYaxis[50] = (int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200;
aZaxis[50] = (int)(((double)rand())/((double)(RAND_MAX)+(double)(1)))*200;

u are just inserting a value only at the last elment of th array . though the array indexing is not correct. Cactus_Hugger and Rashakil Fol has explained why. here is a sample code which give u an idea of getting a randon no. using the library function - srand()

Code:

#include<stdio.h> #include<stdlib.h> int main() { FILE *fp; int array1[10]; int array2[10]; int array3[10]; int i=0; srand(time(NULL)); if((fp=fopen("test102.txt","w"))!=NULL) { for(i=0;i<9;i++) { array1[i]=rand() % 200; array2[i]=rand() % 200; array3[i]=rand() % 200; printf("\n%d\n",fprintf(fp,"%i\t%i\t%i\n ",array1[i],array2[i],array3[i])); } } else { printf("Error: File cannot be opened\n"); getchar(); exit(1); } fclose(fp); getchar(); return 0; } /* myoutput text file text102.txt 173 41 40 19 19 113 112 148 174 141 36 61 75 126 179 42 172 11 97 129 168 172 105 124 73 1 103 */

u can see the randon values with in 200

ssharish2005

Quote:

Originally Posted by ssharish2005

u are just inserting a value only at the last elment of th array .

No. It's being inserted after the last element in the array, as described above.

Quote:

Originally Posted by ssharish2005

Code:

for(i=0;i<9;i++)

You on the other hand, aren't putting anything in the last element of yours. ;)

Quote:

Originally Posted by ssharish2005

Code:

printf("\n%d\n",fprintf(fp,"%i\t%i\t%i\n ",array1[i],array2[i],array3[i]));

*scratches head* Must stop before I get a head-ache...

Quzah.

Code:

printf("\n%d\n",fprintf(fp,"%i\t%i\t%i\n ",array1[i],array2[i],array3[i]));

here is was just checking out the return value for the purpose of debugging. ignore the printf, its just

Code:

fprintf(fp,"%d\t%d\t%d\n",array1[i],array2[i],array3[i]);

and the for loop should be

Code:

for(i=0;i<=9;i++)

thax quzah for pointing it out

ssharish2005