GNU GCC compilor error “multiple definition of main”

Question

I am new to ubuntu, now I need to develop my assignment in C++. I am using codeblocks IDE to write c++ programs. Whenever I compile something in it, it gives these errors:

Answer 1

The program compiles fine with (yourcode.cc contains your sourcecode):

$ CXXFLAGS="-Wall -Werror -Wpedantic" make yourcode

stack.cc: In member function ‘int List::get()’:
stack.cc:76:1: error: control reaches end of non-void function [-Wreturn-type]
 }

and invoking ./yourcode outputs:

 List size = 5

 Element 1 2
 Element 2 6
 Element 3 8
 Element 4 7
 Element 5 1

Obviously your IDE is going to add some flags to the linker. Please show us your compile flags/setting. See the compile log or run the make command executing more verbose.

May have a look at. Code::blocks verbose build

Answer 2

It seems that your IDE is not just compiling one single file, but another one which also contains a definition of the main function. Please check out how many files are being compiled.

In addition, your compiled is treating all the warnings as errors (-Werror) or disable this flag.

Answer 3

The Problem was just, my IDE was compiling multiple files at once, and also in the function int List::get() , I got to add else return -1 at the end of this function after if statement,
I mean before editing my code the int List::get() function was like this:

int List::get() {
    if (currentNode != NULL)
        return currentNode->get();
}

I replaces this one with:

int List::get() {
    if (currentNode != NULL)
        return currentNode->get();
    else return -1;
}

and it worked fine.