CODEWITHSUNDEEP
c++multithreading
Mike Smith
Mike Smith

Reputation: 39

C++ Threading and string help please

I am loosing my mind and new to C++ I know C# where I know that it is as simple as

var cat = "cat";
dvar(0,0, "hi" +cat+ "hi");

My issue here is I am developing a game and need to put a string into a function call like so:

string host = "HIST";
dvar(0,0, "s \"test" + host.c_str() + "connection\"");

Also about the threading I am going nuts because my game I can only call in one function at a time but I have a function that is on scree instructions that has a constant while loop so it's to busy handing that looping thread for me to activate any other functions via buttons.

Upvotes: 0

Views: 121

Answers (2)

ronag
ronag

Reputation: 51253

You should do call the function without the c_str() in order to use the non-member string concatenation function.

dvar(0,0, ("s \"test" + host + "connection\"").c_str());

Since host is a std::string type the + operator will result in calling the non-member function operator+ for std::string.

E.g. host + "connection" will result in calling the following function, where "connection" is implicitly converted into a std::string:

std::string operator+(const std::string& lhs, std::string&& rhs);

However, if you would do host.c_str() + "connection", the compiler would be looking for a function that looks like:

??? operator+(const char* lhs, const char* rhs);

Which doesn't exist in the standard library.

Upvotes: 1

pmr
pmr

Reputation: 59811

The expression:

"s \"test" + host.c_str() + "connection\"

will try to add pointers to char. This cannot work. You might be looking for a string class?

std::string host = "bar";
// this is quite inefficient
func("foo" + host + "baz");
// this is somewhat better
std::string x = "foo";
x.append(host);
x.append("baz");
func(x);

Upvotes: 0

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