C++ errors: ‘string’ does not name a type

Question

when I compile the following files, I've got the error:

ECArgs.h:36:3: error: ‘string’ does not name a type

ECArgs.h:36: ECString value(char c);

Could somebody give me any hints for the error?

ECArgs.h

#include <list>
#include "ECString.h"

class ECArgs
{
 public:
  ECArgs(int argc, char *argv[]);
  int nargs() { return nargs_; }
  bool isset(char c);
  ECString value(char c);
  ECString arg(int n) { return argList[n]; }
 private:
  int nargs_;
  int nopts_;
  ECString argList[32];
  list<ECString> optList;
};

ECString.h

#define ECS gnu

#if ECS == gnu
#include <cstring>
#define ECString string
using namespace std;
#else
#include <bstring.h>
#define ECString string
#endif

Palsy

It's not a "wired" error. It's perfectly reasonable not to recognize a symbol from a non-included header. Also, typedef and using are better solutions for type aliases than #define. – Meshed

@Meshed What do you mean by non-included header? – Palsy

If you want to get access to std::string, you need to #include <string>, not #include <cstring>. – Graviton

Precisely what the answer says. std::string is in <string> and you never include it. Therefore, the compiler is perfectly reasonable in complaining. – Meshed

Are you sure that #if ECS == gnu does what you think it does? It evaluates ECS and gnu as integer constant expressions. How is gnu defined? – Catty

Answer 1

You need to add:

#include <string>

cstring includes function to manipulate C-style string. This version works:

#include <list>
#include <string>

#if ECS == gnu
#include <cstring>
#define ECString string
using namespace std;
#else
#include <bstring.h>
#define ECString string
#endif

class ECArgs
{
 public:
  ECArgs(int argc, char *argv[]);
  int nargs() { return nargs_; }
  bool isset(char c);
  ECString value(char c);
  ECString arg(int n) { return argList[n]; }
 private:
  int nargs_;
  int nopts_;
  ECString argList[32];
  list<ECString> optList;
};

int main()
{

}

Gratulant

Just wondering why cstring doesn't work. I tried to use 'string' in another test.cpp file which just include <cstring>. The test.cpp works well. – Palsy

@EarthWorm Is possible you includes another header files that included string? I am looking at gcc 4.4.4 and several headers include string, including random and stdexcept. – Gratulant

Answer 2

I ran into a similar error. It was due to the fact that I had left out using namespace std;

Alternatively, one has to use std::string for all occurrences of string.

Swiftlet

Yes I guess just typing #include <string> is not enough, need using namespace std; – Nitrite

Answer 3

I had the same error. It didn't work with

#include <string.h>

but started to work as I changed it to

#include <string>

Have no idea why. (Under Microsoft Visual Studio Professional 2022)

Contributor

string.h is a header from the C library with stuff like strlen. string is part of the standard C++ library that defines std::string – Fantinlatour

If you have a new question, please ask it by clicking the Ask Question button. Include a link to this question if it helps provide context. - From Review – Poodle