Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations strongm on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
Random Numbers
- Thread starter Stopher
- Start date
pankajkumar
Programmer
Use rand function example given in msdn or one rerence which i gave in response to qs "Random number output to text file" here...anyway i repeat
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
int main(int argc, char* argv[])
{
int i;
FILE *fp;
fp=fopen("c:\\newtext.txt","w+"
;
/* Seed the random-number generator with current time so that
* the numbers will be different every time we run.
*/
srand( (unsigned)time( NULL ) );
/* Display 10 numbers. */
for( i = 0; i < 10;i++ )
{
char szTemp[64];
printf( " %6d\n", rand() );
_itoa(rand(),szTemp,10);
strcat(szTemp," "
fputs(szTemp,fp);
}
fclose(fp);
return 0;
}
hope it helps
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
int main(int argc, char* argv[])
{
int i;
FILE *fp;
fp=fopen("c:\\newtext.txt","w+"
;/* Seed the random-number generator with current time so that
* the numbers will be different every time we run.
*/
srand( (unsigned)time( NULL ) );
/* Display 10 numbers. */
for( i = 0; i < 10;i++ )
{
char szTemp[64];
printf( " %6d\n", rand() );
_itoa(rand(),szTemp,10);
strcat(szTemp," "
;fputs(szTemp,fp);
}
fclose(fp);
return 0;
}
hope it helps
BoulderBum
Programmer
To elaborate, a call to rand() generates psuedo-random numbers, or "random" numbers that follow a mathmatical pattern. This, of course, isn't truly random, so a "seed" is thrown in to change the pattern of rand() to appear not so random. srand() accmoplishes this, and by passing an ever-changing arguement like system time to srand ( srand( time( 0 ) ) ) you get the effect of actual random numbers.
rand() "returns a value between(inclusive) 0 and and RAND_MAX (defined by the compiler, often 32767). " so to get a random number between a certain range say 0-10, you need to use the modulus operator to shrink the range: rand() % 11. If you want to get a random number between, say 5 and 15 you simply do as above, but use an offset ( 5 in this case so... rand % 11 + 5 ).
rand() "returns a value between(inclusive) 0 and and RAND_MAX (defined by the compiler, often 32767). " so to get a random number between a certain range say 0-10, you need to use the modulus operator to shrink the range: rand() % 11. If you want to get a random number between, say 5 and 15 you simply do as above, but use an offset ( 5 in this case so... rand % 11 + 5 ).
- Thread starter
- #4
- Status