Thread: problem with parser code

hello guys,
i have been stuck with some right now on my design on paser for a simple grammer which is given bellow
L -> ( C )
C -> idC'
C' -> , id C' | E

for the expression
( a , b , c )

the problem with the code is when i return from the function C' to the C the token 'sym' which i read in C' is not the same in C. its true that u can say that all the local varables will destroyed when the control comes out of the function. but in my case i have declared sym variable as globle so that it can be acessed by all the function. and here us code

Code:

char *sym;

void L(char *sym)
{
 	 if(strcmp(sym,"(")==0)
 	 {
   	     sym=getsym();
   	     C(sym);
                     printf("%s",sym);   // so if i print the sym here it has to print ')'but it prints the old which was read by this function first that was id
   		 if(strcmp(sym,")")!=0)
   		 {
			   printf("Error: closing para missing\n");
			   getchar();
			   exit(1);
          	}
	  }
	  else
	  {
		   printf("Error: opening para missing\n");
		   getchar();
		   exit(1);
       	  }
}

void C(char *sym)
{
 	 if(strcmp(sym,"id")==0)
	  {
	   		sym=getsym();
			C1(sym);
       	  }
	   else
	   {
	   	   printf("Error: Identifier missing\n");
		   getchar();
		   exit(1);
	   }
}

void C1(char *sym)
{
 	 if(strcmp(sym,",")==0)
 	 {
	  		sym=getsym();
			if(strcmp(sym,"id")==0)
			{
			 	sym=getsym();
				 C1(sym);
		    	}
			else
			{
			 	printf("Error: Identifier missing\n");
				 getchar();
				 exit(1);
		    	}
    	}

}

any help would be appriciated

ssharish2005

you are right filker0 its was something to do with the parameters. it working fine now. thanks very much for you help.


ssharish2005