连续将一个char数组合并到另一个char数组中[重复]

Question

我想在收到消息的同时不断地将small_buf 合并到big_buffer 中。我不知道该怎么做。

char small_buf[100];
char big_buffer[2048];
ssize_t bytes_r = 0;
while((bytes_r = recv(socket_fd,small_buf,sizeof(small_buf)-1,0)) > 0) {
     small_buf[bytes_r] = '\0';
     // now merge small_buf with big_buffer
}

big_buffer 表示从recv 以较小块的形式接收到的单个大消息。如何将所有 small_buf 合并到 big_buffer 中？

Answer 1

只需将数据接收到缓冲区中：

// the buffer to read the data to
char buffer[2048];
// position in buffer
size_t pos = 0;

for (
        // count of bytes received in this loop or error
        ssize_t received = 0; 
        ( 
             received = recv(socket_fd, 
                 // we are reading into position pos into the buffer
                 &buffer[pos],
                 // the size of buffer decreases each iteration
                 // leave space for zero terminating character `- 1`
                 // I assume that when `pos == sizeof(buffer) - 1` then `recv` will just return 0 or -1.
                 sizeof(buffer) - pos - 1,
                 0)
         # compare received > 0 
         ) > 0; 
         ) {
     // increase the position in buffer
     pos += received;
     // optionally: add `if (pos == sizeof(buffer) - 1) break;`         
     // also assert that all received characters are isprint()
}
// zero terminate the buffer, if you want to
// otherwise remove the `-1` above
buffer[pos] = '\0';

并且没有 cmets：

char buffer[2048];
size_t pos = 0;
for (ssize_t received = 0; 
         ( received = recv(socket_fd, &buffer[pos], sizeof(buffer) - pos - 1, 0)) > 0; 
         ) {
     pos += received;
}
buffer[pos] = '\0';

printf("Received %zu characters: `%.*s`\n", pos, (int)pos, buffer);

终止条件是序列\r\n\r\n有没有办法检测到这个？

char buffer[2048];
size_t pos = 0;
while (7) { // lucky 7!
    const ssize_t received = recv(socket_fd, &buffer[pos], 1, 0);
    // handle error
    // TODO: for example handle EINTR here
    if (received < 0) {
       break;
    }
    // handle empty loop
    if (received == 0) {
       continue;
    }

    // increment position in buffer
    assert(received == 1);
    pos += 1;
    // zero terminate the buffer
    assert(pos < sizeof(buffer));
    buffer[pos] = '\0';

    // if we have more then 4 characters, check for ending sequence
    if (pos >= 4) {
       if (memcmp(buffer[pos - 4], "\r\n\r\n", 4) == 0) {
           // sequence \r\n\r\n found
           break;
        }
    }

    // check for no more memory
    if (pos == sizeof(buffer) - 1) {
        // no more memory
        break;
    }
}