The above poster is not exactly correct.

When you call scanf(), if the function fails (which will happen when you try to read an integer but it is given a character), it will not actually consume the input character from the input. This means the next time you call scanf() it will end up trying to read the same character again!

To catch this, you can check the return value from scanf(). It tells you the number of inputs read successfully. When there is an error it should return less than the number of variables you wanted to read in (in this case, less than 1). If this happens, you need to flush the input stream. The easiest way to do this is just by calling fflush(stdin).

Apparently fflush() is a "bad practice", but in small programs it should be fine. There are other "better" ways to deal with this.