求10000以内的素数
2015-05-27计算一个N值，从2到N遍历取模,如果可以取余，就不是。
1、shell实例
#!/bin/sh
N=$1
if [ -z $1 ];then
echo Usage:$0 num
exit 0
fi
for (( i=2; i<=$N;i++ ));do
flag=0;
for (( j=2;j<=i/2;j++ )); do
if ((i%j==0));then
flag=1;
break;
fi
done
done
if (($flag));then
echo $N is not a prime number;
else
echo $N is a prime number;
fi
2、c实例
#include "stdio.h"
int main(){
int a,b;
int c=10000;
for(a=2;a<=c;a++)
{
for(b=2;b < a;b++) if(a%b==0) break; if(b>=a)
printf("%5d\n",a);
}
return 0;
}
3、python
#!/usr/bin/python
def is_prime(num):
res=True
for x in range(2,num-1):
if num%x==0:
res=False
return res
return res
for x in range(2,1000):
if is_prime(x):
print x
或者
#!/usr/bin/python
import sys
if __name__ == '__main__':
if len(sys.argv) < 2 :
print "please usage %s string "%(sys.argv[0])
sys.exit()
def is_prime(num):
res=True
for x in range(2,num-1):
if num % x == 0:
res=False
return res
n=int(sys.argv[1])
if is_prime(n):
print("%s is a prime" % (n))
else:
print("%s is not a prime" % (n))
4、c实例
#include "stdio.h"
int main(){
int a,b;
int c=1000;
int d=0;
for(a=300;a<=c;a++)
{
for(b=2;b<a;b++) if(a%b==0) break; if(b>=a)
{
printf("%5d ",a);
d++;
if(d%6==0)
printf("\n");
}
}
printf("\n");
printf("row:%5d ",d/6+1);
printf("\n");
printf("totol:%5d ",d);
printf("\n");
return 0;
}