Python 等到？

Question

我正在从先前请求的 url 获取数据。 到目前为止一切正常。

我的问题：我尝试每 X 秒进行一次查询，如果查询显示不同的值，则应该执行某些操作。 但即使在 finalresponseback != notready 时它也会打印 Solving-Capture

 responseback = requests.get('https://2captcha.com/res.php?json=1&action=get&key=' + apikey + "&id=" + finalrequest)

 responseback_json = responseback.json()
 finalresponseback = responseback_json['request']
 print(responseback_json)
 notready = (str("CAPCHA_NOT_READY"))



 while(finalresponseback == notready):
     print("Solving-Capture...")
     if finalresponseback != notready:
         print("Entering...")

Answer 1

这是因为您编写代码的方式，假设 finalresponseback 还没有准备好，那么会发生这种情况：

while(finalresponseback == notready): # This would enable the loop because it's equal to not ready
    print("Solving-Capture...") # It would print this
    if finalresponseback != notready: # Nothing would happen because it is equal to notready
        print("Entering...") # This woudln't happen

但是，如果突然发生变化：

while(finalresponseback == notready): # This happened before it changed
    print("Solving-Capture...") # This also happened before it changed, so it happens anyway
    if finalresponseback != notready: # This happens too
        print("Entering...") # And so does this, so therefore it would print both statements

这段代码很糟糕，因为如果它更改为 notready，那么它将退出循环而不做任何事情，除非它在循环中发生更改，一个更好的版本是：

while(1): # Starts a loop
    if finalresponseback != notready: # Checks finalresponseback
        print("Entering...") # Prints statement
        break # Exits loop
    else: # If it is equal to notready
        print("Solving-Capture...") # Print statement

上面的代码直接检查循环中的 finalresponseback，因此，它将能够打印语句，而不是像以前一样在开始时完全退出。

最后，我们可以添加：

responseback_json = responseback.json()
finalresponseback = responseback_json['request']

到代码以每 x 秒请求一次：

import time # Add to top of code, imports the time library
x = 2 # Sets the x variable
while(1): # Starts a loop
    responseback_json = responseback.json()
    finalresponseback = responseback_json['request']
    if finalresponseback != notready: # Checks finalresponseback
        print("Entering...") # Prints statement
        break # Exits loop
    else: # If it is equal to notready
        print("Solving-Capture...") # Print statement
    time.sleep(x)

最后，一个优化代码的技巧，而不是

notready = (str("CAPCHA_NOT_READY"))

你可以做

notready = "CAPCHA_NOT_READY"

这是因为它已经是一个字符串值（如语音标记“”所示）