Optimera primtalsprogram

#include <stdio.h>

int main(int argc, char *argv[])
{
        int *primes;
        int i,j;
        int max=0;

        if (argc < 2)
        {
                printf("usage: %s <highest prime>\n", argv[0]);
                return 0;
        }

        max = atoi(argv[1]);
        primes = (int *)malloc(sizeof(int) * max);
        memset(primes, 1, sizeof(int) * max);

        for (i=2;i<max;i++)
        {
                j = i * 2;
                while ((primes[i]) && (j < max))
                {
                        primes[j] = 0;
                        j = j + i;
                }
        }

        for (i=2;i<max;i++)
        {
                if (primes[i])
                {
                        printf("%d\n",i);
                }
        }
        free(primes);

        return 0;
}

$n = 100000;
for ($i=3; $i<$n; $i++)
{
	for ($z=2; $z<=sqrt($i); $z++)
	{
		if ($i%$z==0)
		{
			$z=0;
			break;
		}
		
	}
	if ($z!=0)
	{
		$p[] = $i;
	}
}

for ($i=3; $i<$n; $i+=2)

private static boolean checkPrime(int sum)
{
  int n = 0;
  boolean cBool = true;
  if (sum==2 || sum==3)
    cBool = true;
  else if (sum%2==0 || sum%3==0)
    cBool = false;
  else
  {
    while (Math.sqrt(sum) > 6*n+1 && cBool)
    {
      n++;
      if (sum%(n*6-1)==0 || sum%(n*6+1)==0)
        cBool = false;
      else
        cBool = true;
      }
    }
  return cBool;
}

function istrue($var) {
    return($var==1);
}
function findPrimes($topCandidate) {	  
    $array=array_fill(0,$topCandidate,1);        
	  $array[0]=0;
	  $array[1]=0;    
	  $thisFactor=2;
	  while($thisFactor*$thisFactor<=$topCandidate) {
		    $mark=$thisFactor+$thisFactor;
		    while($mark<=$topCandidate)	{
			      $array[$mark]=0;
			      $mark+=$thisFactor;
			  }
		    $thisFactor++;
		    while($array[$thisFactor]==0) {
            $thisFactor++;
        }
		}    
    return count(array_filter($array, "istrue"));
}
$topCandidate = 100000;
echo findPrimes($topCandidate);

		private void button1_Click(object sender, System.EventArgs e)
		{
			//System.Text.StringBuilder sb = new System.Text.StringBuilder();
	        System.DateTime tStart, tEnd;
	        tStart = System.DateTime.Now;

			bool blnPrime;
			for (int i=1;i<=1000000;i++)
			{
				blnPrime = checkPrime(i);
				//if (blnPrime)
				//	sb.Append(String.Format("{0}, ", i));
			}
			tEnd = System.DateTime.Now;
			textBox1.Text = tEnd.Subtract(tStart).ToString();
			//textBox1.Text = sb.ToString();
		}

		private void button2_Click(object sender, System.EventArgs e)
		{
			System.DateTime tStart, tEnd;
			tStart = System.DateTime.Now;

			string tmp = printPrimes(1000000);
			
			tEnd = System.DateTime.Now;
			textBox2.Text = tEnd.Subtract(tStart).ToString();
		} 


		private string printPrimes(int max)
		{
			//System.Text.StringBuilder sb = new System.Text.StringBuilder();
			ArrayList al = new ArrayList();
			int prime;

			int k=1, x;
			al.Add(3);

			if (max >= 5) {
				for (x=5;x<max;x+=2){
					prime = 1;
					for (int z=0;z<k;z++){
						if (x%(int)al[z] == 0){
							prime = 0;
							break;
						}
						if (Math.Pow((int)al[z],2) >= x){
							break;
						}
					}
					if (prime == 1){
						k++;
						al.Add(x);
					}
				}
				//sb.Append(String.Format("Det finns {0} primtal mellan 1 och {1}:", k, max));
				//sb.Append("1, ");
				//for (x=0;x<k;x++)
				//	sb.Append(String.Format("{0}, ", al[x]));
			}else{
				//sb.Append("1, 2, 3");
			}
			return "";
		}


		private static bool checkPrime(int sum)
		{
			int n = 0;
			bool cBool = true;
			if (sum==2 || sum==3)
				cBool = true;
			else if (sum%2==0 || sum%3==0)
				cBool = false;
			else
			{
				while (Math.Sqrt(sum) > 6*n+1 && cBool)
				{
					n++;
					if (sum%(n*6-1)==0 || sum%(n*6+1)==0)
						cBool = false;
					else
						cBool = true;
				}
			}
			return cBool;
		}

    $max=1000000;
    $primes=array_fill(0,$max,1); ;    
    for ($i=2;$i<$max;$i++) {
        $j = $i * 2;
        while (($primes[$i]) && ($j < $max)) {
            $primes[$j] = 0;
            $j = $j + $i;
        }
    }
    for ($i=2;$i<$max;$i++) {
        if ($primes[$i]) {
            $nr++;
        }
    }
    echo $nr;