學習目標：

生成一個從2到1000的質數字典並儲存為檔案primes.txt 格式如下（以下是從2到10質數字典）：

2

3

5

7

# -*- coding: UTF-8 -*-

from math import sqrt

def isPrime(num):
    flag = 0
    for i in range(num):
        if i == 0 or i == 1:
            continue
        if i == 2:
            f.write(str(i)+'\n')
            continue
        for j in range(2,int(sqrt(i)+1)):
            if i%j == 0:
                flag = 1
                break
        if flag == 1:
           flag =0
        else:
            f.write(str(i)+'\n')

f = open("primes.txt","w")
isPrime(1000)
f.close()