Since you already know the range of the sequence, and it's small, and you want non-repeating values, a random shuffle would be a better option than trying to check whether each new number was already generated or not:

C Syntax (Toggle Plain Text)

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
#define N 157
 
int main ( void )
{
  int seq[N];
  int i;
 
  srand ( (unsigned)time ( NULL ) );
 
  /* Initialize seq to an ordered range */
  for ( i = 0; i < N; i++ )
    seq[i] = i;
 
  /* Random shuffle */
  for ( i = 0; i < N - 1; i++ ) {
    int r = ( rand() % ( N - i ) + 1 );
    int save = seq[i];
    seq[i] = seq[i + r];
    seq[i + r] = save;
  }
 
  /* Test the sequence */
  for ( i = 0; i < N; i++ )
    printf ( "%d ", seq[i] );
 
  return 0;
}

#include <stdio.h> #include <stdlib.h> #include <time.h> #define N 157 int main ( void ) { int seq[N]; int i; srand ( (unsigned)time ( NULL ) ); /* Initialize seq to an ordered range */ for ( i = 0; i < N; i++ ) seq[i] = i; /* Random shuffle */ for ( i = 0; i < N - 1; i++ ) { int r = ( rand() % ( N - i ) + 1 ); int save = seq[i]; seq[i] = seq[i + r]; seq[i + r] = save; } /* Test the sequence */ for ( i = 0; i < N; i++ ) printf ( "%d ", seq[i] ); return 0; }

Not only is it easier to verify, it's also considerably faster.