help! "clang: error: linker command failed with exit code 1 (use -v to see invocation)"

[zeddy]

Program:
#include <iostream>
using namespace std;
//prototypes
void DemonstrateProc1();
void DemonstrateProc2(int num);
int main()
{
cout << "?. Execution starts with main. " << endl;
DemonstrateProc1();
cout << "?. Then we come here. " << endl;
DemonstrateProc2(100);
cout << "?. Finally we come here. "<< endl;
return 0;
}

output:
Undefined symbols for architecture x86_64:
"DemonstrateProc1()", referenced from:
_main in lab9-b16905.o
"DemonstrateProc2(int)", referenced from:
_main in lab9-b16905.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

How can I fix this error?

[AbstractionAnon]

So where are DemonstrateProc1 and DemonstrateProc2 implemented?
You have function prototypes for them, but no implementation.

PLEASE ALWAYS USE CODE TAGS (the <> formatting button) when posting code.
It makes it easier to read your code and also easier to respond to your post.
http://www.cplusplus.com/articles/jEywvCM9/
Hint: You can edit your post, highlight your code and press the <> formatting button.