RAND_MAX

#define RAND_MAX /*implementation defined*/

Expands to an integer constant expression equal to the maximum value returned by the function rand(). This value is implementation dependent. It's guaranteed that this value is at least 32767.

Example

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
int main(void)
{
    srand(time(NULL)); // use current time as seed for random generator
    printf("RAND_MAX: %i\n", RAND_MAX);
    printf("INT_MAX: %i\n", INT_MAX);
    printf("Random value on [0,1]: %f\n", (double)rand() / RAND_MAX);
}

RAND_MAX: 2147483647
INT_MAX: 2147483647
Random value on [0,1]: 0.362509

References

• C17 standard (ISO/IEC 9899:2018):
• 7.22/3 General utilities <stdlib.h> (p: 248)
• C11 standard (ISO/IEC 9899:2011):
• 7.22/3 General utilities <stdlib.h> (p: 340)
• C99 standard (ISO/IEC 9899:1999):
• 7.20/3 General utilities <stdlib.h> (p: 306)
• C89/C90 standard (ISO/IEC 9899:1990):
• 4.10 GENERAL UTILITIES <stdlib.h>

See also