The ask program prompts the user and accepts a single-key response.

The options can appear anywhere on the command line.

The “prompt string” and responses are positional parameters. They must be in order.

System Exit Code: In an sh-compatible shell, you check the ?* variable.
In a batch file you check the ERRORLEVEL.
Other shells may be different.

• The user must press Enter after pressing a key.
• The response is not case-sensitive by default. Use -c if case-sensitive mode is necessary.
• If the user presses more than one key, the first key will be used. The user can use the keyboard to edit their response.
• The escape sequences \, \a, \n, \r, and \t are allowed in the prompt string.

ask “** Answer [Y]es, [N]o, or [M]aybe: ” YNM

The example displays the following prompt, and reads the user’s response:

** Answer [Y]es, [N]o, or [M]aybe:

The example returns:

• Exit code 1 if the user pressed y or Y.
• Exit code 2 if the user pressed n or N.
• Exit code 3 if the user pressed m or M.
• Exit code 0 if the user pressed a key that was not y, Y, n, N, m, or M.
• Exit code 126 if the user pressed Enter without pressing a key.
• Exit code 127 if the user pressed Escape.

You can include the ask_funcs.h header and link the ask_funcs.o module to your own C/C++ programs. This provides your programs the same functionality used by the ask program.

It uses standard C library functions for I/O. It uses the standard putchar() function to print the prompt string to stdout, and the standard getchar() function to read the response character from stdin.

The ask_funcs module provides the following public functions:

void set_default_options();
void set_case_sensitive_mode(int value);
int ask(char *prompt, char *response_list);

void set_default_options();

• The set_default_options function simply sets the default case_sensitive mode option to OFF (0).

void set_case_sensitive_mode(int value);

• The set_case_sensitive_mode function lets you turn the case sensitive mode ON (non-zero) or OFF (0).

int ask(char *prompt, char *responses);

• The ask function lets you prompt the user, specifying the prompt string and the response characters, and then receive the response code.
• The return value from the ask function is the same as the system exit codes described for the ask program.