g++ complaining about STD functions

Question

I have a section of downloaded source code, when trying to compile via Cygwin using g++ compiler, the compiler gives me an error saying that the 'transform' function is undeclared in this scope...

I am using the std namespace, and I have the correct headers. I am not sure why it is not compiling.. The syntax looks correct

Here is the code block section.

string tolower (const string & s)
  {
    string d = s;
    transform(d.begin(), d.end(), d.begin(), (int(*)(int)) tolower);
    return d;
  }  // end of tolower

Here is my header section:

#include <fcntl.h>
#include <signal.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>

// standard library includes ...

#include <string>
#include <list>
#include <map>
#include <set>
#include <vector>
#include <stdexcept>
#include <fstream>
#include <iostream>
#include <sstream>
#include <ios>
#include <iterator>

using namespace std;

Sorry, but -1 *"and I have the correct headers"* No, clearly you don't — Manu343726, Aug 04 '14 at 15:50

score 5 · Answer 1 · edited May 23 '17 at 11:57

5

You need to include the appropriate header for std::transform:

#include <algorithm>

You should also avoid using namespace std; in the global namespace in headers, you pollute the global namespace of any code that includes your header file.

See this post about using namespace std.

edited May 23 '17 at 11:57

Community

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answered Aug 04 '14 at 15:47

juanchopanza

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that ought to do it. Thank you. – Uys of Spades Aug 04 '14 at 15:50
re "You should also void using namespace std; in headers", I would restrict that advice to the global namespace in headers, and anyway there's no evidence that the OP is doing that. – Cheers and hth. - Alf Aug 04 '14 at 15:51
@Cheersandhth.-Alf How is there no evidence? The last line in OP's code is `using namespace std;`… – The Paramagnetic Croissant Aug 04 '14 at 15:52
@Cheersandhth.-Alf check the last line of the question. – Manu343726 Aug 04 '14 at 15:52
i mean, there's no evidence that that is a header file. – Cheers and hth. - Alf Aug 04 '14 at 15:53
@Cheersandhth.-Alf Agreed about the global namespace. I interpreted "header section" to mean header file, but you're right, it is not unambiguous. – juanchopanza Aug 04 '14 at 15:53

g++ complaining about STD functions

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