Why we need #include <string>

[vcc]

I am new to C++. I've read in section #include <string>
They said that we must #include <string> before using string data type, but it is still run when i do not put #include <string> line.

Please explain!

Thanks

[jsmith]

You might be including other header files that include string.

[vcc]

Here is my code:

#include <iostream>
using namespace std;
int main()
{
string str = "Hello World"; // I think i should error here with unknown data type
cout << str;

return 0;
}

thanks

[helios]

Nope. No error. It seems iostream includes string as well. As simple as that.

[Duthomhas]

I think your compiler is just being nice to you. <iostream> is not required (actually, it is not supposed to) #include <string>. If you using strings, you should #include <string>, whether or not your particular compiler lets you get away without it.

[helios]

Just for the record, I was using MinGW, but Duoas is right. Don't depend on the particular headers to do the inclusion for you.

[vcc]

I am using Dev-C++ 4.9.9.2. Yes, I get the point. However, can you explain more details? or link me the other resource on the web.

[eker676]

I never noticed that.. I used the older version of dev c++ and it wouldn't allow that.

The compiler notices that you are using a 'string' variable type and automatically adds in the correct header file without you knowing. Its best practice to declare the headers and not to rely on the compiler to do it.

Here is some functions of the <string> header
http://www.cplusplus.com/reference/clibrary/cstring/

What exactly are you looking for? Reference to the header itself or why the compiler allows the string variable without the header file.

[jsmith]

No, that is the C string library. The C++ string library is the one in question:

http://www.cplusplus.com/reference/string/

[eker676]

My mistake, sorry.