Python程序似乎永远运行而不在终端中输出答案

【问题标题】：Python program seems to run forever without outputting in terminalPython程序似乎永远运行而不在终端中输出
【发布时间】：2021-04-04 21:13:14
【问题描述】：

我一直在研究一个库来实现 RSA 加密方法，这个文件（以及我一直在研究的其他文件）不输出，而是在执行脚本后只在终端输出一个空行。我已经通过自动评分器运行它，它超时了。下面是库的代码，但有些东西告诉我我的问题可能是解释器问题或文件本身之外的问题。看起来它可能在到达 return 或 output 语句之前就卡住了。我还附上了terminal output.的截图

import stdio
import stdrandom
import sys


# Generates and returns the public/private keys as a tuple (n, e, d). Prime numbers p and q
# needed to generate the keys are picked from the interval [lo, hi).
def keygen(lo, hi):
    primes = []
    for i in range(lo, hi):
        if _primes(0, i):
            primes += [i]

    ptemp = stdrandom.uniformInt(0, len(primes))
    qtemp = stdrandom.uniformInt(0, len(primes))
    p = primes[ptemp]
    q = primes[qtemp]
    n = p * q
    m = (p - 1) * (q - 1)
    while True:
        e = stdrandom.uniformInt(2, m)
        if e % m == 0 and m % e != 0:
            break
    d = 0
    for a in range(1, m):
        if (e * a) % m == 1:
            d = a
            break
    return n, e, d


# Encrypts x (int) using the public key (n, e) and returns the encrypted value.
def encrypt(x, n, e):
    return (x ** e) % n


# Decrypts y (int) using the private key (n, d) and returns the decrypted value.
def decrypt(y, n, d):
    return (y ** d) % n


# Returns the least number of bits needed to represent n.
def bitLength(n):
    return len(bin(n)) - 2


# Returns the binary representation of n expressed in decimal, having the given width, and padded
# with leading zeros.
def dec2bin(n, width):
    return format(n, '0%db' % (width))


# Returns the decimal representation of n expressed in binary.
def bin2dec(n):
    return int(n, 2)


# Returns a list of primes from the interval [lo, hi).
def _primes(lo, hi):
    primes = []
    for p in range(lo, hi + 1):
        j = 2
        f = 1
        while(j * j <= p):
            if(p % j == 0):
                f = 0
                break
            j = j + 1
        if(f == 1):
            primes += [p]
    return primes


# Returns a list containing a random sample (without replacement) of k items from the list a.
def _sample(a, k):
    b = a.copy()
    c = b[0:k]
    stdrandom.shuffle(c)
    return c


# Returns a random item from the list a.
def _choice(a):
    random = stdrandom.uniformInt(0, len(a))
    return random



# Unit tests the library [DO NOT EDIT].
def _main():
    x = ord(sys.argv[1])
    n, e, d = keygen(25, 100)
    encrypted = encrypt(x, n, e)
    stdio.writef('encrypt(%c) = %d\n', x, encrypted)
    decrypted = decrypt(encrypted, n, d)
    stdio.writef('decrypt(%d) = %c\n', encrypted, decrypted)
    width = bitLength(x)
    stdio.writef('bitLength(%d) = %d\n', x, width)
    xBinary = dec2bin(x, width)
    stdio.writef('dec2bin(%d) = %s\n', x, xBinary)
    stdio.writef('bin2dec(%s) = %d\n', xBinary, bin2dec(xBinary))


    if __name__ == '__main__':
        _main()

【问题讨论】：

很可能存在无限循环。检查while True 循环中的逻辑。
@iz_ 可以。感谢您的输入

标签： python output

【解决方案1】：

正如@iz_ 建议的那样，您的代码中有一个无限循环。这段代码：

while True:
    e = stdrandom.uniformInt(2, m)
    if e % m == 0 and m % e != 0:
        break

永远不会退出，因为e 将始终小于m，因此e % m == 0 将始终为False。直到e % m == 0 为真，循环才会退出，这永远不会发生。

【讨论】：