getting segmentation fault if I dont pass any command line parameters

[doni]

Hi,

I am a beginner to C and I wrote a program that takes arguments and
prints it in hex. I am getting a segmentation fault if I dont pass any
arguments instead I want it to display the Usage message that I have.

Here is my simple program.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char * argv[])
{
char buffer[100];
char ch, * string;
int i, a=0;

if (argc < 1) {
printf("Usage: test <IPv4 Address\n");
}
else {
string = argv[1];
strcpy(buffer, string);
a = strlen(buffer);
printf("a value is: %d", a);
for (i = 0; i < a; i++)
{
printf("Value is: %02x\n", buffer[i]);
//printf("Value is: %X\n", buffer[i]);
}
}
}

Thanks,
doni

[Ben Pfaff]

doni <do********@gma il.comwrites:

if (argc < 1) {
printf("Usage: test <IPv4 Address\n");
}

argc is almost always at least 1 in a hosted environment, because
argv[0] is used to contain the program's name. You should be
testing whether argc is less than 2.
--
int main(void){char p[]="ABCDEFGHIJKLM NOPQRSTUVWXYZab cdefghijklmnopq rstuvwxyz.\
\n",*q="kl BIcNBFr.NKEzjwC IxNJC";int i=sizeof p/2;char *strchr();int putchar(\
);while(*q){i+= strchr(p,*q++)-p;if(i>=(int)si zeof p)i-=sizeof p-1;putchar(p[i]\
);}return 0;}

[CBFalconer]

doni wrote:

>
Hi,

I am a beginner to C and I wrote a program that takes arguments and
prints it in hex. I am getting a segmentation fault if I dont pass any
arguments instead I want it to display the Usage message that I have.

Here is my simple program.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char * argv[])
{
char buffer[100];
char ch, * string;
int i, a=0;

if (argc < 1) {
printf("Usage: test <IPv4 Address\n");
}
else {
string = argv[1];
strcpy(buffer, string);
a = strlen(buffer);
printf("a value is: %d", a);
for (i = 0; i < a; i++)
{
printf("Value is: %02x\n", buffer[i]);
//printf("Value is: %X\n", buffer[i]);
}
}
}

Try: "if (argc < 2) ...".

When printing an address (i.e. a) use the %p specifier, and cast
the address to void*.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>

--
Posted via a free Usenet account from http://www.teranews.com

[Army1987]

On Tue, 30 Oct 2007 15:30:13 -0500, CBFalconer wrote:

doni wrote:

[...]

> int i, a=0;

[...]

> printf("a value is: %d", a);

[...]

When printing an address (i.e. a) use the %p specifier, and cast
the address to void*.

Huh? What address?
--
Army1987 (Replace "NOSPAM" with "email")
A hamburger is better than nothing.
Nothing is better than eternal happiness.
Therefore, a hamburger is better than eternal happiness.

[doni]

On Oct 30, 11:42 am, Ben Pfaff <[e-mail] rd.eduwrote:

doni <doni.se...@gma il.comwrites:

if (argc < 1) {
printf("Usage: test <IPv4 Address\n");
}

argc is almost always at least 1 in a hosted environment, because
argv[0] is used to contain the program's name. You should be
testing whether argc is less than 2.
--
int main(void){char p[]="ABCDEFGHIJKLM NOPQRSTUVWXYZab cdefghijklmnopq rstuvwxyz.\
\n",*q="kl BIcNBFr.NKEzjwC IxNJC";int i=sizeof p/2;char *strchr();int putchar(\
);while(*q){i+= strchr(p,*q++)-p;if(i>=(int)si zeof p)i-=sizeof p-1;putchar(p[i]\
);}return 0;}

Thanks, Ben.

doni

[CBFalconer]

Army1987 wrote:

CBFalconer wrote:

>doni wrote:

[...]

>> int i, a=0;

[...]

>> printf("a value is: %d", a);

[...]

>When printing an address (i.e. a) use the %p specifier, and cast
the address to void*.

Huh? What address?

Wasn't any. I read too quickly and carelessly.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>

--
Posted via a free Usenet account from http://www.teranews.com