string和string.c_str（）的值不同

Question

i'm trying to send a file through the network using c++. first of all, i read my file and buffer it into a string and then i convert my string to c_str() and send it by my socket class

i have a problem with when i send my data, it doesn't output correctly. i wrote the following code to check that and i realize that the value of my string and string.c_str() is different from each other

ifstream source(path.c_str(), ios::binary);   
ostringstream out;
out << source.rdbuf();

string msg = out.str();

source.close();

cout << "msg: " << msg << endl;
printf("sent - %s\n", message.c_str());

the result of this two line is different. "cout" prints my file's characters but printf just print 3 characters

why this happen?

thanks a lot your help

Answer 1

看来该字符串在第三个字符之后包含嵌入的零“ \\ 0”。