将字符串转换为字节数组

Question

I was wondering if there was a C++ equivalent to Javas .getBytes() method. I'm reading a .txt file and need to convert each line into bytes.

Thanks in advance!

Answer 1

In C++ a char is a byte. And so a std::string is already a sequence of bytes.

However, you may want a sequence of unsigned char .

One way is to just copy the byte values from the string, eg into a std::vector :

using Byte = unsigned char;
vector<Byte> const bytes( s.begin(), s.end() );

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If you're reading the text file into a std::wstring per line, eg using a wide stream, then the bytes depend on your preferred encoding of that string.

In practice, except possibly on an IBM mainframe, a C++ wide string is either UTF-16 or UTF-32 encoded. For these two encodings the standard library provides specializations of std::codecvt that can convert to and from UTF-8.

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If you want an arbitrary encoding from a wide string, then you're out of luck as far as the C++ standard library is concerned, sorry.

Answer 2

std::string::data 是等价的。