Scratch that: apparently they weren't all in the same project when I did that, so I added all of them to a project and tried to compile. This time my errors list was much bigger:

Projects/Main.cpp:3:20: iostream: No such file or directory
Projects/Main.cpp: In function `int main()':
Projects/Main.cpp:18: `cout' undeclared (first use this function)
Projects/Main.cpp:18: (Each undeclared identifier is reported only once for
each function it appears in.)
Projects/Main.cpp:27: `cin' undeclared (first use this function)

make.exe: *** [Projects/Main.o] Error 1

Execution terminated

Apparently, it's not reading my #include <iostream> and using namespace std; lines. How can I fix this?