Thread: Arrays of pointers (input)

Hello, why is it that i can't get string literals and asign them to pointer variables with scanf() and printf()?

Code:

#include <stdio.h>

main()
{
	char * name[3]; /* An array of pointers to characters */

	fgets(name[0], 81, stdin); /* Get a string literal */
	puts(*name);

	/* printf("%s\n", name[0]); why won't this function work? It always returns(NULL) */
	/* Also, scanf("%s", name[0]); doesnt' work for getting input either */

return 0;

}

Thanks,
Tyler

Might wish to check again. It is all working a ok with my computers.

Code:

#include <stdio.h>
int main(void)
{
char * name[3]; /* An array of pointers to strings */
/*fgets(name[0], 81, stdin);*/
/*name[0][strlen(name[0])-1]='\0';*/  /*Using to remove the newline character when using fgets */
scanf("%s", name[0]);
/*puts(*name);*/
printf("**%d**", printf("%s\n", name[0]));

return 0;
}

Code:

#include <stdio.h>
int main(void)
{
char * name[3]; /* An array of pointers to strings */
fgets(name[0], 81, stdin);
name[0][strlen(name[0])-1]='\0';  /*Using to remove the newline character when using fgets */
/*scanf("%s", name[0]);*/
/*puts(*name);*/
printf("**%d**", printf("%s\n", name[0]));

return 0;
}

The the other combos, they all work just fine.

Thanks for your prompt replies!

...I'm using the gcc compiler from Delories web site....

Code:

C:\>gcc -o new new.c
new.c:12:2: warning: no newline at end of file



C:\>new

kj /* This is the characters i pressed */
(null)
**7**

C:\>gcc -o new new.c
new.c:12:2: warning: no newline at end of file




C:\>new

lj /* This is the characters i pressed */
Exiting due to signal SIGSEGV
General Protection Fault at eip=00001622
eax=ffffffff ebx=00000298 ecx=0000000d edx=00000000 esi=00000054 edi=0000f970
ebp=0008f950 esp=0008f930 program=C:\DOCUME~1\TYLER\DESKTOP\PROGRAMS\NEW.EXE
cs: sel=01a7  base=02980000  limit=0009ffff
ds: sel=01af  base=02980000  limit=0009ffff
es: sel=01af  base=02980000  limit=0009ffff
fs: sel=017f  base=0000dd70  limit=0000ffff
gs: sel=01bf  base=00000000  limit=0010ffff
ss: sel=01af  base=02980000  limit=0009ffff
App stack: [0008f970..0000f970]  Exceptn stack: [0000f8d0..0000d990]

Call frame traceback EIPs:
  0x00001622
  0x00002e38

It gaves me this same crap every time.
Thanks,
Tyler

Kinasz,
your code does the same as mine, thanks though. Maybe it's the compiler.

Thantos,
I downloaded the compiler from:
http://www.delorie.com/djgpp/zip-picker.cgi
I don't think it has specific versions.
Thanks,

Tyler

type:
gcc -v

and it should output the version.

One problem is with not allocating enough memory for the strings (bow Kinasz). Try this code out. With full warnings in effect on GCC and running through Splint with only one warning it should work.

Code:

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

int main(void)
{
  char *name[3];

  *name = malloc (3 * sizeof (char) * 81);

  if ( name == NULL)
  {
    (void)puts("Error getting memory");
    return 1;
  }

  (void)fgets(name[0], 81, stdin);
  (void)printf("***%d***\n", printf("%s", name[0]));

  free(*name);
  return 0;
}

Thanks so much! That's awesome! It worked!


Yet, i'v never seen this done before:

Code:

(void)printf("***%d***\n", printf("%s", name[0]));

Did you type cast the printf() function as type void or something? And the printf function within the printf function is wierd.


..Oh ya, the gcc version is 3.3.2

Thanks again...
Tyler

The type casting is something I did to shut splint up. Since printf returns a value if you don't use it splint wants it casted to (void) so its for sure an ignored value.
Yea the printf in a printf is a first for me to. But since you mentioned that it was returning NULL I thought of a way to easily check the return value.

Thanks man.
Tyler