You see build errors but it doesnt prompt before executing the project/program.
Here microsoft visual studio Options may be changed.
Follow the steps to make it work fine.
1) Go to "Tools" option on the top of the visual studio as shown below figure1.
2) Select "Options" in the Tools menu.
3) Options Popup Box you see Tree View Items, Expand Projects and Solutions.
4) Select Build and Run Option.
5) After selecting you see couple of dropDowns on the right side section.
6) Where you see "On Run, when build or deployment errors occur:" select "Prompt to Launch" in the below DropDown.
7) Click "OK"... Thats it you are ready to Go.