Question

继承我的代码：

std::string message(m_buff.begin(), m_buff.end());

std::cout << "Client wrote sth!" << std::endl;
std::cout << message.c_str() << std::endl;

如果我在最后一行设置断点，启动debuger并查找m_buff var，有一些数据，但它没有显示。

继承数据（来自调试器）：

m_buff  [0x00000400](0x00,0x08 '',0x22 '"',0x00,0x57 'W',0x6f 'o',0x57 'W',0x00,0x03 '',0x03 '',0x05 '',0x34 '4',0x30 '0',0x36 '6',0x38 '8',0x78 'x',0x00,0x6e 'n',0x69 'i',0x57 'W',0x00,0x45 'E',0x44 'D',0x65 'e',0x64 'd',0x3c '<',0x00,0x00,0x00,0x05 '',0x6c 'l',0x19 '',0x1c '',0x04 '',0x46 'F',0x47 'G',0x47 'G',0x47 'G',0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,...,...)  std::vector<unsigned char,std::allocator<unsigned char> >

Answer 1

假设调试器显示的数据是正确的，好像你的消息缓冲区中有一些二进制零。

请记住，二进制0（'\0'）用于表示字符串的结尾。因此，由于m_buff的第一个元素是零，因此该字符串的长度为0。

您应该迭代m_buff并将所有字节打印为十六进制序列 - 或过滤掉任何0个字符（也许还有其他不可打印的字符） - 取决于您的确切意图是什么）。

Answer 2

扩展Alexander的答案（这是正确的），如果您真的想将二进制数据写入标准输出，请按照以下方式进行：

std::cout.write(&m_buff[0], m_buff.size());

Answer 3

使用c_str()时，它返回字符串的文本内容，后跟NUL终止符。你的字符串的“文本”内容也以0x00开头 - 一个NUL终结符。因此，看作C风格的ASCIIZ文本，你的字符串是空的（operator<<(std::ostream&, const char*)必须解释它的参数，因为c_str（）转换阻止使用operator<<(std::ostream&, const std::string&)来访问正确size() {1}} - 知道std::string。所以 - ASCIIZ在前面有一个“Z”：什么都不会显示。

如果你想以一些可见的屏幕形式显示NUL，你必须选择一些表示，例如“\ 000”，“”无论如何，并在你的字符串中移动一个字符，一次决定要打印什么

如果您只想以二进制形式写出数据，请不要使用c.str()：您还可以使用std::cout.write(address, number_of_bytes)作为二进制输出，提供&message[0]的地址， message.data()甚至message.c_str()虽然您不需要额外的NUL终止，但实施不当可能会浪费时间和内存创建一个，以及size()。

C ++ std :: vector <uint8>已填充，但未显示数据</uint8>

3 个答案: