Thread: simple frontend program problem

> I don't use TAB because Vim already does it for me.....
Then set it to use 4 spaces, not one TAB character.
Whether you physically press the tab key is irrelevant, there are tab chars in your code, and it looks a mess posted here.

> I think arg_list[0] = "mpg321" is ok as long as this pointer does not deal with NULL.
Wrong - you can only delete what you got with new
Since "mpg321" isn't from new, then delete will likely barf all over you.

I suggest you use opendir() readdir() closedir() for getting directory listings.

Hard to say what is wrong with your two examples, since neither compiles, and its too short to guess the context in which they're being used.
In any event, you should really specify the full path to the name of the program being run "/bin/ls" instead of just "ls"

>In any event, you should really specify the full path to the name of the program being >run "/bin/ls" instead of just "ls"

I learn about system call from http://www.advancedlinuxprogramming.com . Here's why I choose not to specify the full path of the program.


.....................
The exec functions replace the program running in a process with another program.
When a program calls an exec function, that process immediately ceases executing that
program and begins executing a new program from the beginning, assuming that the
exec call doesn't encounter an error.
Within the exec family, there are functions that vary slightly in their capabilities
and how they are called.


1 Functions that contain the letter p in their names (execvp and execlp) accept a
program name and search for a program by that name in the current execution
path; functions that don't contain the p must be given the full path of the pro-
gram to be executed.


2 Functions that contain the letter v in their names (execv, execvp, and execve)
accept the argument list for the new program as a NULL-terminated array of
pointers to strings. Functions that contain the letter l (execl, execlp, and
execle) accept the argument list using the C language's varargs mechanism.
3 Functions that contain the letter e in their names (execve and execle) accept an
additional argument, an array of environment variables.The argument should be
a NULL-terminated array of pointers to character strings. Each character string
should be of the form "VARIABLE=value".
Because exec replaces the calling program with another one, it never returns unless an
error occurs.
The argument list passed to the program is analogous to the command-line argu-
ments that you specify to a program when you run it from the shell.They are available
hrough the argc and argv parameters to main. Remember, when a program is
nvoked from the shell, the shell sets the first element of the argument list argv[0]) to
he name of the program, the second element of the argument list (argv[1]) to the
irst command-line argument, and so on.When you use an exec function in your pro-
grams, you, too, should pass the name of the function as the first element of the argu-
ment list.
......................


What do you think about that? It said if I use execvp that use 'p' character, I don't need to specify the full path of the program I use.

Beside that I accept your suggestion fully.