Small piece of code compilation problem

[Charles Leng]

I have been having a problem compiling a short simple piece of code. The code is not my own but taken from 'C++: A Beginner's Guide' by Herbert Schildt 2nd Edition, Chapter 7 Listing 2 p245. I have just added a few lines necessary to see the program output in a console window. The listing is as follows and is identical to the code presented in the book bar the few minor alterations. I don't think the alterations would be the cause of the problem at all. Here is the code in question:

include <cstdlib>

include <iostream>

using namespace std;

int negate(const int *val);

int main(int argc, char *argv[])
{
int result;
int v = 10;

result = negate(&v);

cout << v << " negated is " << result; 
cout << "\n";

system("PAUSE");
return EXIT_SUCCESS;

}

int negate(const int val)
{
return - val;
}

// End of code

Here is the compiler output:

Line File Message
C:\Dev-Cpp\Templates\Listing_2.cpp In function int main(int, char**)': 13 C:\Dev-Cpp\Templates\Listing_2.cppnegate' undeclared (first use this function)
(Each undeclared identifier is reported only once for each function it appears in.)
C:\Dev-Cpp\Templates\Listing_2.cpp In function int negate(const int*)': 23 C:\Dev-Cpp\Templates\Listing_2.cppint negate(const int*)' used prior to declaration
C:\Dev-Cpp\Makefile.win [Build Error] [Templates/Listing_2.o] Error 1

I don't know what is the cause of this. I would have thought such simple example code as this would compile with a standard C++ compiler. I am using Dev-C++ 4.9.9.2 on Windows Xp Professional SP2. I also encountered the same problem when using Dev-C++ 4.9.9.2 on Windows 98 SE. Perhaps others can copy and paste this sample code into their Dev-C++ IDE and try and compile to see if they get the same result. I would be most interested to know what happens.

Thanks in advance

[Wayne Keen]

Does this compile any different for you?

include <cstdlib>

include <iostream>

using namespace std;

int my_negate(const int *val);

int main(int argc, char *argv[])
{
int result;
int v = 10;

result = my_negate(&v);

cout << v << " negated is " << result;
cout << "\n";

system("PAUSE");
return EXIT_SUCCESS;
}

int my_negate(const int val)
{
return - val;
}

// End of code

It compiles and runs for me under MinGW/MSYS (GCC-4.2.1) - I don't have Dev on this machine

Wayne

[Charles Leng]

Yes this did compile differently with the desired result. Thankyou for the tip.

[cpns]

I am willing to bet that negate is defined somewhere in the std:: namespace.

There's a reason for namespaces, and "using namespace std ;" undoes all that it attempts to solve!

[Wayne Keen]

That was going to be my next question to the OP - "Why does this work when I changed the function
name?"

:)

Wayne

[Charles Leng]

I don't know why but it did work.

Charles Leng

[cpns]

... because "negate" is defined in namespace std::