Question

我正在使用Python。我试图用递归方法计算。我使用count+=1时出错。这是为什么？当我使用sum=sum+count时，我也会收到错误。这是错误：

分配前引用的
局部变量'count'

这是我的代码：

def receiveOnePing(mySocket, ID, timeout, destAddr):
    #receives ping
    timeLeft = timeout
    while 1:
        startedSelect = time.time()
        whatReady = select.select([mySocket], [], [], timeLeft)
        howLongInSelect = (time.time() - startedSelect)
        if whatReady[0] == []: # Timeout
            return "Request timed out."
        timeReceived = time.time()
        recPacket, addr = mySocket.recvfrom(1024)  
        header = recPacket[20:28]
        type, code, checksum, id, sequence= struct.unpack("bbHHh", header)     
        if id ==ID:
            sizeofdouble = struct.calcsize("d")#returns size of structure
            timeSent = struct.unpack("d", recPacket[28 : 28+sizeofdouble])[0]
            print "Type:%d Code:%d Checksum:0x%08x Packet ID:%d Sequence:%d RTT:%d ms % (type, code, checksum, id, sequence, rtt)
            count+=1
        timeLeft = timeLeft - howLongInSelect
        if timeLeft <= 0:
            return "Request timed out."
        else :
            return "REPLY from %s " % destAddr

Answer 1

您尚未将名称计数分配给对象。您需要在引用计数之前指定计数。尝试：

count = 0

在尝试count += 1之前。

Answer 2

你没有在行打印上结束字符串“Type ....你需要在这一行上有一个结束引号。

Answer 3

在count=0

之前添加timeLeft = timeout

在递归方法中保持计数？

3 个答案: