Here's a small programme that will search through all command line parameters and print each out. It will also scan each parameter and print whether or not it contains all digits (leading whitespace is discarded such that " 123" is considered all digits. It should illustrate how to know when to stop processing command line arguments.
Arguments from the command line are zero terminated. From the example above the statement for( ; *sp; sp++ ) will stop when the character pointed to by sp is zero. It is the same as using:
So, to answer your question about what *argv[1]+4 will equal when argv[1] is "eric" -- it should be zero.
I have a program which I wish to modify. It used to be run from the command line, but now I wish to change this so it can be used as a function.
The program has complex argument processing so I want to pass my paramters to as if it were being called by the OS as a program.
I have tried to... (2 Replies)
Hi C experts,
I have the following code for adding command line option for a program
int main (argc, argv)
int argc;
char *argv;
{
char *mem_type; //memory type
char *name; //name of the memory
int addr; //address bits
int data; ... (5 Replies)
Hello Friends,
I got stuck with fgets () & rewind() function .. Please need help..
Actually I am doing a like,
The function should read lines from a txt file until the function is called..
If the data from the txt file ends then it goes to the top and then again when the function is called... (1 Reply)
this is in one of my scripts...
if ($#argv == 0) then
echo 'blah bla'
exit 0
endif
I want it to be something like this...
if ($#argv == 0 OR $argv >=3)
echo 'blah bla'
exit 0
endif
so when the arguments are none, or greater than three I want this "if then" to take over. how? I... (5 Replies)
SCO openserver 5r5
I only have this available to me ...
To list the files...
cpio -itcvB < /dev/nrct0
To copy a file out
cpio -icvdBum filename < /dev/nrct0So cpio is to archive or "zip" files up??
and /dev/nrct0 is the tape drive ???
How can i list all the files inside... (2 Replies)
when i run my program, i have a parameter, that i want to set the value to another string
i am using
int main(int argc, char **argv) {
char my_str=argv;
printf("%s",my_str);
return 0;
}
and i get
Segmentation fault
ran using
./my_prog /usr/share/dict/words hello1
... (2 Replies)
All of my machines (various open source derivatives on x86 and amd64) store argv above the stack (at a higher memory address). I am curious to learn if any systems store argv below the stack (at a lower memory address).
I am particularly interested in proprietary Unices, such as Solaris, HP-UX,... (9 Replies)
So i am trying to read in file
readFile <GivenFile> modFile
looking for a regular file under the directories in the GivenFile and print them out is my over all goal.
basically I am looking for anything that looks like a directory in the given file and printing it out.
Since I am trying to do... (2 Replies)
Discussion started by: squidGreen
2 Replies
LEARN ABOUT ULTRIX
getopt
getopt(3) Library Functions Manual getopt(3)Name
getopt - get option letter from argument vector
Syntax
#include <stdio.h>
int getopt (argc, argv, optstring)
int argc;
char **argv;
char *optstring;
extern char *optarg;
extern int optind, opterr;
Description
The subroutine returns the next option letter in argv that matches a letter in optstring. The optstring is a string of recognized option
letters; if a letter is followed by a colon, the option is expected to have an argument that may or may not be separated from it by white
space. The optarg is set to point to the start of the option argument on return from
The function places in optind the argv index of the next argument to be processed. The external variable optind is automatically initial-
ized to 1 before the first call to
When all options have been processed (that is, up to the first non-option argument), returns EOF. The special option -- may be used to
delimit the end of the options; EOF will be returned, and -- will be skipped.
Diagnostics
The function prints an error message on stderr and returns a question mark (?) when it encounters an option letter that is not included in
optstring. Setting opterr to 0 disables this error message.
Examples
The following code fragment shows how one might process the arguments for a command that can take the mutually exclusive options a and b,
and the options f and o, both of which require arguments:
#include <stdio.h>
main (argc, argv)
int argc;
char **argv;
{
int c;
extern int optind, opterr;
extern char *optarg;
.
.
.
.
while ((c = getopt (argc, argv, "abf:o:")) != EOF)
switch (c) {
case 'a':
if (bflg)
errflg++;
else
aflg++;
break;
case 'b':
if (aflg)
errflg++;
else
bproc( );
break;
case 'f':
ifile = optarg;
break;
case 'o':
ofile = optarg;
bufsiza = 512;
break;
case '?':
errflg++;
}
if (errflg) {
fprintf (stderr, "usage: . . . ");
exit (2);
}
for ( ; optind < argc; optind++) {
if (access (argv[optind], 4)) {
.
.
.
}
See Alsogetopt(1)getopt(3)