Final answer:
The return value of 'scanf()' tells you the number of input items successfully read and assigned, or EOF on end-of-file or error, while 'getchar()' returns the next character read as an int, or EOF on end-of-file or error.
Step-by-step explanation:
Understanding the Return Values of scanf() and getchar()
The return values of scanf() and getchar() are indicators used in C programming to determine the outcome of input functions. scanf() is a function that reads formatted input from the standard input (stdin) and returns the number of input items successfully matched and assigned, which can be useful for error checking. If scanf() reaches the end-of-file (EOF) before any input can be read or if a reading error occurs, it returns EOF.
On the other hand, getchar() is a function that reads the next character from the standard input and returns it as an integer. This return value represents the character read as an unsigned char cast to an int. In the case where the end-of-file is encountered or a reading error occurs, getchar() also returns EOF. However, since getchar() is meant to read a single character, its return value does not provide information about the number of characters read, unlike scanf().
Understanding the return values of these functions is crucial for error handling in C programs. For instance, by checking the return value of scanf(), developers can determine whether the expected amount of data was received, while checking the return value of getchar() can signal if the function has reached the EOF or if an error occurred during reading.