segmentation fault

hi everyone . i am new to the fourm and i was trying to compile a file using gcc to catenate two string but keep getting a segmentation fault
this is the source code

Code:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
     int main()
{
   int x;
   char *pring,*ding;
   printf("\n enter any string ");
   scanf("%s",pring);
   printf("\n enter another string");
   scanf("%s",ding);
  
   x=sizeof(pring)+sizeof(ding)+22;
   pring=realloc(pring,x);
   strcat(pring,ding);
 
   printf("\n%s",pring);
   return 0;
}

This is the message i get when i try to debug it with gdb :
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7aade97 in _IO_vfscanf () from /lib/libc.so.6

can anyone help me out with this ??

You should find a good tutorial on malloc() and how it should be used. That'd explain away all the issues you're having here.

Code:

char *pring,*ding;

You haven't allocated memory for those char pointer, but still your trying read in a string. Wghcih is wrong. Try allocate memory before reading any value. For example

Code:

if( ( pring = malloc( 80 ) ) != NULL )
     scanf("%s", pring);
...
...
free(pring);

ssharish

The problem is that you have not allocated space for pring and ding before reading data into them.

Safer should be

Code:

if( ( pring = malloc( 80 ) ) != NULL )
     if( 1==scanf("%79s", pring) ) puts("input was OK");
...
...
free(pring);

in fact its better to use fgets instead of scanf function reading string avoid buffer overfollow and stdin standoff of '\n' char.

ssharish