undefined reference to `_WinMain@16' related to Namespace STD?

[dayhuffguy]

Hello Everyone,

I am currently using eclipse to try and do some pretty basic C++. When I was trying to configure I noticed G++ was giving me an error. When I troubleshot the problem I found that if I added the namespace std it would compile fine. Why is this?

Code with namespace:

#include "TestClass.h"
using namespace std;
 
TestClass::TestClass()
{
}
 
TestClass::~TestClass()
{
}
int main() 
{
    return 0;
}
 

Compiling messages without:
**** Clean-only build of configuration Release for project UseDLL ****
Build complete for project UseDLL

**** Build of configuration Release for project UseDLL ****

make all
Building file: ../src/DllTest.cpp
Invoking: Cygwin C++ Compiler
g++ -O3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/DllTest.d" -MT"src/DllTest.d" -o"src/DllTest.o" "../src/DllTest.cpp"
Finished building: ../src/DllTest.cpp

Building target: UseDLL.exe
Invoking: Cygwin C++ Linker
g++ -o"UseDLL.exe" ./src/DllTest.o
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libcygwin.a(libcmain.o):(.text+0xab): undefined reference to `_WinMain@16'
collect2: ld returned 1 exit status
make: *** [UseDLL.exe] Error 1

[Banfa]

Building target: UseDLL.exe
Invoking: Cygwin C++ Linker
g++ -o"UseDLL.exe" ./src/DllTest.o
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libcygwin.a(libcmain.o):(.text+0xab): undefined reference to `_WinMain@16'
collect2: ld returned 1 exit status
make: *** [UseDLL.exe] Error 1

This error is nothing to do with namespace standard.

You have told the linker that you are compiling a windows program (through the use of switches on your command line). The entry point for Windows programs is WinMain, however you have provided main which is the entry point for console programs (on a windows system) and ANSI C programs.