4月27日去迈瑞面试，要求写一个循环缓冲类，真心没接触过，结果可想而知。
下午回到实验室，认真写了一下，完成代码贴出来。
1: //mindry_buffer.h
2:
3: #ifndef MINDRY_BUFFER_H_H
4: #define MINDRY_BUFFER_H_H
5:
6: class CMindryBuffer
7: {
8: public:
9: bool isFull();//缓冲区是否满
10: bool isEmpty();//缓冲区是否空
11: void Empty();//置空缓冲区
12: int GetLength();//缓冲区大小
13:
14: CMindryBuffer(int size);
15: virtual ~CMindryBuffer();
16:
17: int Write(char * buf, int count);//写缓冲
18: int Read(char * buf, int count);//读缓冲
19:
20: private:
21: bool m_bEmpty;//缓冲区空标识
22: bool m_bFull;//缓冲区满标识
23:
24: char * m_pBuf;//缓冲区指针
25: int m_nBufSize;//缓冲区大小
26: int m_nReadPos;//读数据位置
27: int m_nWritePos;//写数据位置
28:
29: };
30:
31: #endif
1: //mindry_buffer.cpp
2: #include "mindry_buffer.h"
3: #include <cstring>
4:
5: CMindryBuffer::CMindryBuffer(int size)
6: {
7: m_nBufSize = size;
8: m_nReadPos = 0;
9: m_nWritePos = 0;
10: m_pBuf = new char[m_nBufSize];
11: m_bEmpty = true;
12: m_bFull = false;
13: }
14:
15: CMindryBuffer::~CMindryBuffer()
16: {
17: delete[] m_pBuf;
18: }
19:
20: int CMindryBuffer::Write(char *buf, int count)
21: {
22: if(count <= 0) return 0;
23:
24: m_bEmpty = false;//buffer is full
25:
26: if(m_bFull)
27: {
28: return 0;
29: }
30: else //if(m_nReadPos == m_nWritePos) //buffer is empty
31: {
32: /*
33: empty m_nReadPos empty
34: |-------------------------|---------------------------| m_nBufSize
35: m_nWritePos
36: */
37: int rightcount = m_nBufSize - m_nWritePos;
38: if(rightcount > count)//space is enough
39: {
40: memcpy(m_pBuf + m_nWritePos, buf, count);
41: m_nWritePos = (m_nWritePos + count)%m_nBufSize;
//m_nWritePos += count;
42: m_bFull = (m_nWritePos == m_nReadPos);
43: return count;
44: }
45: else
46: {
47: memcpy(m_pBuf + m_nWritePos, buf, rightcount);
48: m_nWritePos = (m_nReadPos > count - rightcount) ?
49: count - rightcount : m_nWritePos;//is left space enough?yes,copy;no, no action;
50: memcpy(m_pBuf, buf + rightcount, m_nWritePos);
51: m_bFull = (m_nWritePos == m_nReadPos);
52: return rightcount + m_nWritePos;
53: }
54: }
55:
56: /*
57: empty m_nReadPos m_nWritePos empty
58: |-----------------|------------------|-------------------| m_nBufSize
59: data rightcount
60: */
61: else //if(m_nReadPos < m_nWritePos)//buffer is not full
62: {
63: int rightcount = m_nBufSize - m_nWritePos;
64: if(rightcount > count) //rest space is enough
65: {
66: memcpy(m_pBuf + m_nWritePos, buf, count);
67: m_nWritePos = (m_nWritePos + count)%m_nBufSize;
//m_nWritePos += count;
68: m_bFull = (m_nReadPos == m_nWritePos);
69: return count;
70: }
71: else//rest space is not enough
72: {
73: memcpy(m_pBuf + m_nWritePos, buf, rightcount);
74: m_nWritePos = (m_nReadPos > count - rightcount) ?
75: count - rightcount : m_nReadPos;
76: memcpy(m_pBuf, buf + rightcount, m_nWritePos);
77: m_bFull = (m_nWritePos == m_nReadPos);
78: return rightcount + m_nWritePos;
79: }
80: }
81: }
82:
83: int CMindryBuffer::Read(char *buf, int count)
84: {
85: if(count < 0) return 0;
86:
87: m_bFull = false;
88: if(m_bEmpty)
89: {
90: return 0;
91: }
92: else //if(m_nReadPos == m_nWritePos) //buffer is full
93: {
94: /*
95: data m_nReadPos data
96: |--------------------|--------------------|m_nBufSize
97: m_nWritePos rightcount
98: */
99: int rightcount = m_nBufSize - m_nReadPos;
100: if(rightcount > count)
101: {
102: memcpy(buf, m_pBuf + m_nReadPos, count);
103: m_nReadPos = (m_nReadPos + count)%m_nBufSize;
//m_nReadPos += count;
104: m_bEmpty = (m_nReadPos == m_nWritePos);
105: return count;
106: }
107: else
108: {
109: memcpy(buf, m_pBuf + m_nReadPos, rightcount);
110: m_nReadPos = (m_nWritePos >= count - rightcount) ?
111: count - rightcount : m_nWritePos;
112: memcpy(buf + rightcount, m_pBuf, m_nReadPos);
113: m_bEmpty = (m_nReadPos == m_nWritePos);
114: return rightcount + m_nReadPos;
115: }
116:
117: }
118: else //if(m_nReadPos < m_nWritePos)
119: {
120: /*
121: m_nReadPos data m_nWritePos
122: |-----------------|----------------|-----------------|m_nBufSize
123:
124: */
125: int rightcount = m_nWritePos - m_nReadPos;
126:
127: int temp = (rightcount > count) ? count : rightcount;
128: memcpy(buf, m_pBuf + m_nReadPos, temp);
129: m_nReadPos = (m_nReadPos + temp)%m_nBufSize;
//m_nReadPos += temp;
130: m_bEmpty = (m_nWritePos == m_nReadPos);
131: return temp;
132: }
133: else if(m_nReadPos > m_nWritePos)
134: {
135: /*
136: data m_nWritePos m_nReadPos data m_nBufSize
137: |------------------|------------------|--------------------|
138:
139: */
140: int rightcount = m_nBufSize - m_nReadPos;
141:
142: if(rightcount > count)
143: {
144: memcpy(buf, m_pBuf + m_nReadPos, count);
145: m_nReadPos = (m_nReadPos + count)%m_nBufSize;
//m_nReadPos += count;
146: m_bEmpty = (m_nWritePos == m_nReadPos);
147: return count;
148: }
149: else
150: {
151: memcpy(buf, m_pBuf + m_nReadPos, rightcount);
152: m_nReadPos = (m_nWritePos > count - rightcount) ?
153: count - rightcount : m_nWritePos;
154: memcpy(buf, m_pBuf, m_nReadPos);
155: m_bEmpty = (m_nWritePos == m_nReadPos);
156: return rightcount + m_nReadPos;
157: }
158: }
159: }
160:
161:
162: int CMindryBuffer::GetLength()
163: {
164: if(m_bEmpty)
165: {
166: return 0;
167: }
168: if(m_bFull)
169: {
170: return m_nBufSize;
171: }
172: if(m_nReadPos < m_nWritePos)
173: {
174: return m_nReadPos - m_nWritePos;
175: }
176: else
177: {
178: return m_nBufSize - (m_nReadPos - m_nWritePos);
179: }
180: }
181:
182:
183: void CMindryBuffer::Empty()
184: {
185: m_nReadPos = 0;
186: m_nWritePos =0;
187: m_bEmpty = true;
188: m_bFull = false;
189: }
190:
191: bool CMindryBuffer::isEmpty()
192: {
193: return m_bEmpty;
194: }
195:
196: bool CMindryBuffer::isFull()
197: {
198: return m_bFull;
199: }
1: #include "mindry_buffer.h"
2: #include <iostream>
3: using namespace std;
4:
5: int main(int argc, char * argv[])
6: {
7: CMindryBuffer * mindrybuffer = new CMindryBuffer(100);
8: char * datachar = new char[40];
9: char * reschar = new char[20];
10:
11: int res = 0;
12: int res0 = 0;
13:
14: for(int i=0; i < 40; ++i)
15: {
16: datachar[i] = i + 1;
17: }
18:
19: res = mindrybuffer->Write(datachar, 40);
20: printf("write total:%d
", res);
21: res = mindrybuffer->Write(datachar, 40);
22: printf("write total:%d
", res);
23: res = mindrybuffer->Write(datachar, 40);
24: printf("write total:%d
", res);
25: res = mindrybuffer->Write(datachar, 40);
26: printf("write total:%d
", res);
27:
28: res0 = mindrybuffer->Read(reschar, 20);
29: printf("read total:%d
", res0);
30:
31: res = mindrybuffer->Write(datachar, 40);
32: printf("write total:%d
", res);
33: res = mindrybuffer->Write(datachar, 40);
34: printf("write total:%d
", res);
35: res = mindrybuffer->Write(datachar, 40);
36: printf("write total:%d
", res);
37:
38: for(int j=0; j < 20; ++j)
39: {
40: if(j % 10 == 0) cout<<endl;
41: printf("%d ",reschar[j]);
42: }
43: return 0;
44: }
问题：面试的主管说我之前写的代码不合规范，请各位大牛指点一下。
（面试的时候没有能够实现方法，但是基本的框架结构都和这个是一样）