Problems That May Occur at Execution Time

Programs might not work on the first try. Each of the preceding phases can fail because of various errors that we’ll discuss throughout this book. For example, an executing program might try to divide by zero (an illegal operation for integer arithmetic in C++). This would cause the C++ program to display an error message. If this occurred, you’d have to return to the edit phase, make the necessary corrections and proceed through the remaining phases again to determine that the corrections fixed the problem(s). [Note: Most programs in C++ input or output data. Certain C++ functions take their input from cin (the standard input stream; pronounced “see-in”), which is normally the keyboard, but cin can be redirected to another device. Data is often output to cout (the standard output stream; pronounced “see-out”), which is normally the computer screen, but cout can be redirected to another device. When we say that a program prints a result, we normally mean that the result is displayed on a screen. Data may be output to other devices, such as disks and hardcopy printers. There is also a standard error stream referred to as cerr. The cerr stream (normally connected to the screen) is used for displaying error messages.