麻烦参照理解传递 [英] Trouble understanding pass by reference
问题描述
我真的感到很困惑通过在C#参考了解通。在我的代码我有函数,有两个参数
私人布尔SerialUnEscape(字节serialData,楼盘字节serialResult)
{
如果(((SerialProcessValue)serialData == SerialProcessValue.SERIAL_PACKET_START)||
((SerialProcessValue)serialData == SerialProcessValue.SERIAL_PACKET_END)){
serialEscaped = FALSE;
serialResult = 0;
回报(真);
}
}否则,如果(serialEscaped){
如果((SerialProcessValue)serialData == SerialProcessValue.SERIAL_PACKET_ESCAPE_START){
serialResult =(INT) SerialProcessValue.SERIAL_PACKET_START;
serialEscaped = FALSE;
回报(真);
}
}其他{
serialResult = serialData;
回报(真);
}
}
我打电话用的功能引用作为 serialDataLsb
&安培; serialDataMsb
。
现在我的困惑左右,这将是 serialDataLsb <值/ code>或
serialDataMsb
,
是否得到的值 serialResult
??
为(i = 0; I< serialElements;我++){
serialDataLsb = 0;
serialDataMsb = 0;
,而(serialBufferWalk< serialIndex){
如果(SerialUnEscape(serialBuffer [serialBufferWalk ++],参考serialDataLsb)){
中断;
}
}
,而(serialBufferWalk< serialIndex){
如果(SerialUnEscape(serialBuffer [serialBufferWalk ++],参考serialDataMsb)){
中断;
}
}
serialElementData [I] =(UINT16)(serialDataLsb +(serialDataMsb<< 8));
}
和我需要移植的代码到Python,1)我怎样才能实现路过的Python参考
我试图用这个
而serialBufferWalk< serialIndex:
如果self.SerialUnEscape(serialBuffer [serialBufferWalk + = 1],serialDataLsb):
突破
,而serialBufferWalk< serialIndex:
如果self.SerialUnEscape(serialBuffer [serialBufferWalk + = 1],serialDataLsb):
突破
< DIV CLASS =h2_lin>解决方案
如果你真的想模仿传递按引用而不是改变你的代码返回值,你可以用你想在一个对象来改变原始。为简单起见,我用一个列表:
高清change_reference(byteContainer):
byteContainer [0] = 42
B = 123
打印(二)#123打印
#中的数据复制到容器列表。
容器= [B]
#传递一个指针列表到函数。
change_reference(集装箱)
#取值从容器中。
B =容器[0]
打印(二)#打印42
这使你的功能但实际上混淆。你真正应该做的是包括在返回值修改后的字节:
高清test_and_subtract(V):
如果v == 1:
返回(v - 1,真)
返回(v - 2,假)
V = 1
V,b = test_and_subtract(五)
打印(五)#0
打印(二)#真
V = 5
V,b = test_and_subtract(v)
打印(五)# 3
打印(二)#假
下面收益(v - 1,真)
是把两种结果变成一个元组,而 b,v
是从元组删除它们。
I find it really confusing to understand pass by reference in c#. In my code I have function which takes two parameters
private bool SerialUnEscape(byte serialData, ref byte serialResult)
{
if (((SerialProcessValue)serialData == SerialProcessValue.SERIAL_PACKET_START) ||
((SerialProcessValue)serialData == SerialProcessValue.SERIAL_PACKET_END)) {
serialEscaped = false;
serialResult = 0;
return (true);
}
} else if (serialEscaped) {
if ((SerialProcessValue)serialData == SerialProcessValue.SERIAL_PACKET_ESCAPE_START) {
serialResult = (int)SerialProcessValue.SERIAL_PACKET_START;
serialEscaped = false;
return (true);
}
} else {
serialResult = serialData;
return (true);
}
}
I am calling the function with a reference as serialDataLsb
& serialDataMsb
.
Now my confusion is about, what would be the value of serialDataLsb
or serialDataMsb
,
Does it get the value of serialResult
??
for (i = 0; i < serialElements; i++) {
serialDataLsb = 0;
serialDataMsb = 0;
while (serialBufferWalk < serialIndex) {
if (SerialUnEscape(serialBuffer[serialBufferWalk++], ref serialDataLsb)) {
break;
}
}
while (serialBufferWalk < serialIndex) {
if (SerialUnEscape(serialBuffer[serialBufferWalk++], ref serialDataMsb)) {
break;
}
}
serialElementData[i] = (UInt16)(serialDataLsb + (serialDataMsb << 8));
}
and i need to port this code into python, 1) how can i implement the pass by reference in python
I tried using this
while serialBufferWalk < serialIndex:
if self.SerialUnEscape(serialBuffer[serialBufferWalk += 1],serialDataLsb):
break
while serialBufferWalk < serialIndex:
if self.SerialUnEscape(serialBuffer[serialBufferWalk += 1],serialDataLsb):
break
If you really want to imitate pass-by-reference instead of changing your code to return the value, you can wrap the primitive you want to change in an object. For simplicity, I used a list:
def change_reference(byteContainer):
byteContainer[0] = 42
b = 123
print(b) # Prints 123
# Copy the data into the container list.
container = [b]
# Pass a pointer to that list into the function.
change_reference(container)
# Take the value out of the container.
b = container[0]
print(b) # Prints 42
This makes your function really confusing though. What you should really do is include the modified byte in the return value:
def test_and_subtract(v):
if v == 1:
return (v - 1, True)
return (v - 2, False)
v = 1
v, b = test_and_subtract(v)
print(v) # 0
print(b) # True
v = 5
v, b = test_and_subtract(v)
print(v) # 3
print(b) # False
Here return (v - 1, True)
is putting both results into a tuple, and b, v
is removing them from that tuple.
这篇关于麻烦参照理解传递的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!