查找2到n之间的质数

Question

I am trying to find the number of prime numbers between 2 and n, where n is provided by the user. I can't seem to make it work. here's my code:

>>> def numOfPrime(n):
    count = 0
    for i in range(2,n):
        p = True
        for j in range(2,i):
            if i % j ==0:
                p = False
    if  p == True:
        count += 1

    return count

>>> numOfPrime(100)
0

Answer 1

The indentation of your if block is incorrect. It should be in the loop.

def numOfPrime(n):
    count = 0
    for i in range(2,n):
        p = True
        for j in range(2,i):
            if i % j ==0:
                p = False
        if  p == True:
            count += 1

    return count

Now numOfPrime(100) returns 25, which correctly accounts for 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97.