C++ String - Out of scope error - c++

Question

I was trying to play around with Strings in a Hangman program that I'm writing and couldn't get them to work so tried working with them on a simpler basis and I'm still having no luck.
As far as I've read online in the references and what other people have said this code should work:
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
int main (int argc, char** argv){
string word = {"Hello"};
int length = strlen(word);
}
But I get this compiler error:
'string' was not declared in this scope
and consequently, 'word' is also not declared in scope.
Can anyone see what I'm doing wrong? I'm using the g++ compiler on Ubuntu if that makes a difference, no idea which version though.

Answer 1

You are confusing C and C++.
You included only C libraries, whereas std::string comes from the C++ header string. You'd have to write:
#include <string>
to use it. However, you'd then have to make other changes, such as not using strlen.
You should learn from your C++ book, not random posts on the internet (#lolirony)
C version
#include <string.h>
int main(void)
{
const char* word = "Hello";
const size_t length = strlen(word); // `size_t` is more appropriate than `int`
return 0;
}
C-like C++ version
#include <cstring>
using namespace std;
int main()
{
const char* word = "Hello";
const size_t length = strlen(word);
}
Idiomatic C++ version (recommended)
#include <string>
int main()
{
const std::string word = "Hello";
const std::size_t length = word.size();
}

Answer 2

'string' was not declared in this scope
You need to include the header <string> and refer to it as std::string. Also, strlen does not understand std::string or any user defined types, but you can use the size() method instead:
#include <string>
int main()
{
std::string word = "Hello";
size_t length = word.size();
}

Answer 3

<cstring> is the header for C++ support of C-style null-terminated strings. You should include <string>.

Answer 4

You haven't included the C++ string header in your project.
#include <string>
The libraries that you've included are all plain-C headers.
Additionally, strlen() doesn't work with a c++ string; you should use word.size() instead.

Answer 5

string is a specialization of standard class std::basic_string . It is declared in header <string>
So if you want "to play around with standard class std::string:" you need to include directive
#include <string>
Header <cstring> is not the same as header <string> and contains declarations of standard C functions such as strlen.
However there is no any sense to apply function strlen to an object of type std::string The compiler in this case will issue an error.
I advice you to play with the following code that to see the difference
#include <iostream>
#include <string>
#include <cstring>
int main (int argc, char** argv)
{
std::string word = "Hello";
std::string::size_type length = word.length();
std::cout << "Object word of type std::string has value "
<< word << " with length of " << length
<< std::endl;
std::cout << "The size of the object itself is " << sizeof( word ) << std::endl;
char another_word[] = "Hello";
size_t another_length = std::strlen( another_word );
std::cout << "Object another_word of type char [6] has value "
<< another_word << " with length of " << another_length
<< std::endl;
std::cout << "The size of the object itself is " << sizeof( another_word ) << std::endl;
}