line 11 and line 19: struct and class definition must end with a semicolon.
line 34: statement ends with a semicolon.
line 40: function name is "displayChoices()", not "dispalyChoices()".
line 37: main() must return "int".
line 32: the return type is needed here, ie, void DrinkMachine::displayChoices().
line 8: I think #include<string> is needed here, though no warning or error message appears.
Your code style is very good to make your code readable.
[edit] Chances are you'll have to manually add the MinGW directory to your Toolchain Executables directory list. If you are using Dev-C++, your version of MinGW is horribly out of date... you might as well delete it and download and install the latest version.
i recommend using MinGW as a compiler in Code::Blocks. you can download the mingw32 version of code blocks. this is way easier as you dont have to do all the cofiguration when installing the ide all you do is select GNU C/C++ compiler as your default.