次の例は、primelib.cファイルの内容を示しています。

#include <stdio.h>
#include <math.h>

/*
 * utility functions which are called from the main source code
 */

// Find and return our highest value to check -- which is the square root
int findMaxCheck( int inValue )  {
  float sqRoot;
  sqRoot = sqrt( inValue );
  printf("Square root of %d is %lf\n", inValue, sqRoot); 
  return floor( sqRoot );
  return inValue/2;
}

int debugFlag = 0;

// Search for a factor to the input value, proving prime on return of zero
int seekFactorA( int input, int maxtry )  {
  int divisor, factor = 0;
  for( divisor=2; divisor<=maxtry; ++divisor ) {
    if( 0 == input%divisor ) {
      factor = divisor;
      break;
    }
    else if ( debugFlag != 0 )
      printf( "modulo %d yields: %d\n", divisor, input%divisor );
  }
  return factor;
}

// Search for a factor to the input value, proving prime on return of zero
// This is a different method than "A", using one argument
int seekFactorB( int input )  {
  int divisor, factor = 0;
  if( 0 == input%2 ) return 2;
  for( divisor=3; divisor<=input/2; divisor+=2 ) {
    if( 0 == input%divisor ) {
      factor = divisor;
      break;
    }
  }
  return factor;
}