Length of a string

I am working on a challenge, and I need to find out how many characters are in a string. I have tried size() and length() but they both give me an error (undeclared identifier). But aren't those two functions in the string header? Also, what is the differences between the two headers cstring and string?


EDIT: Oh, and I am using MSVC++6

You need to specify what you mean by "string". There's two kinds of strings.

Code:

---

// C++ strings
#include <string>
#include <iostream>

using namespace std;

int main()
{
    string s("a string");

    cout<< s.length() <<endl;
}

---

Code:

---

// C strings
#include <cstring>
#include <iostream>

int main()
{
    char s[] = "a string";

    cout<< strlen(s) <<endl;
}

---

Quote:

---

Also, what is the differences between the two headers cstring and string?

---

cstring works with C strings, it's the namespace'd version of C's string.h header file. string is the C++ header that contains the std::string class and all of it's necessary functions.

>> cstring works with C strings

C strings being character arrays (namely char* or char[]).

I ment a string (the kind declared in string...not a character array). So I just guessed you could figure it out.

Quote:

---

Originally posted by Munkey01
I ment a string (the kind declared in string...not a character array). So I just guessed you could figure it out.

---

Code:

---

#include <string>
#include <iostream>

using namespace std;

int main(int argc, char** argv)
{
    string message("Hello World!");
    cout << message << "\tmessage is " << message.size() << " characters long!\n";
    return 0;
}

---

>So I just guessed you could figure it out.
If size() and length() didn't work then I had to assume you were doing something wrong or not using the std::string. Most likely your problem is that you're not using namespaces correctly. Try adding a

Code:

---

using namespace std;

---

directive in your code if it's not there and see how it works. Usually I'll get an error saying that so and so is an undeclared identifier if I forget to resolve it from the std namespace.

No, acually my problem was that I wasn't thinking of size() or length() has member functions. I was using them like-

Code:

---

for (int i=0; i<size(sentence); i++)
//and
for (int j=0; j<length(sentence); j++)

---

But your code example showed me what I was doing wrong.