How to deal with char array which '\0' is inserted into? - c++

Question

When I try to copy a struct into a char array buffer using memcpy function, '\0' is inserted into the char array. I pass the buffer pointer to a function. the content before the first '\0' is past, but the rest is lost. How can I solve this problem? I would appreciate it if you help me.
here is the code, although the the struct Mystruct and the function display() is not designed reasonably。
#include <QCoreApplication>
#include <stdio.h>
struct MyStruct
{
char c;
int order;
char ch;
MyStruct(char c = 'b', int order = 0, char ch = 'a'):order(order), ch(ch), c(c)
{};
};
void display(char* str)
{
printf("%s", str);
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyStruct *mystruct = new MyStruct;
// char* test = new char[50];
char test[50];
memset(test, 0, 50);
memcpy(test, mystruct, sizeof(MyStruct));
display(test);
return a.exec();
}
I want to send struct like 'Mystruct' through socket and the function send(char*) requires a char* pointer pointing to a buffer. The '\0' is inserted into the char array when the int order is copied into the test[50].
We use QTcpSocket::write(char* ) of QT instead of APIs offered by Linux or Windows. And my teammate offer me an interface function send(char ).I need pass the buffer pointed to by the char pointer.
I simplized my question with the code showed and apologize for my confusing expression.And any good way to send the struct through socket?

Answer 1

C-string function works with nul-terminating string.
if you want to handle char* with nul non terminal string, you need size (or other sentinel).
MyStruct mystruct;
std::string buffer {(char*) &mystruct, sizeof (MyStruct)};
Demo
Notice that that way of serializing has lot of pitfall:
padding (you might see random value between c and order and also after ch (those 0 ARE random)).
endianess issue.
...