strtok() not splitting string correctly

[LucasBishop]

Hi everyone; i'm working with a program that can't split a strig of characters if i introduce out of the program.
It only work's if the string is put it directly in the the soucer code, here it is:

#include<stdio.h>
#include<string.h>
#include<conio.h>
#include<ctype.h>
#include<stdlib.h>
 
int evaluar(char *simbolo)
{
 if(strcmp(simbolo,"el")==0 || strcmp(simbolo,"la")==0)
  return 0;
 if(strcmp(simbolo,"ni¤o")==0 || strcmp(simbolo,"ni¤a")==0 || strcmp(simbolo,"escuela")==0 || strcmp(simbolo,"casa")==0)
  return 1;
 if(strcmp(simbolo,"camina")==0)
  return 2;
 if(strcmp(simbolo,"lentamente")==0)
  return 3;
 if(strcmp(simbolo,"por")==0)
  return 4;
 if(strcmp(simbolo,"y")==0)
  return 5;
 if(strcmp(simbolo,"bonita")==0 || strcmp(simbolo,"lento")==0)
  return 6;
 if(simbolo=='\0')
  return 7;
 return 8;
}
 
void main ()
{
 int tabla[7][8]={{1,6,6,6,6,6,6,6},
          {6,2,6,6,6,6,6,6},
          {6,6,3,6,0,0,4,10},
          {6,6,6,5,6,6,4,10},
          {6,6,3,6,0,6,6,10},
          {6,6,6,6,0,6,6,6},
          {6,6,6,6,6,6,6,-1}};
 int entrada, col, estado=0, ind=0;
 char *simbolo=NULL, cadena[80];
 int flag=0;
 clrscr();
 printf("Introduzca la cadena -> ");
 scanf("%s",cadena);
 do
 {
  if(simbolo!=NULL)
  {
   simbolo=strtok('\0'," ");
   col=evaluar(simbolo);
  }
  if(flag==0)
  {
   flag=1;
   simbolo=strtok(cadena," ");
   col=evaluar(simbolo);
  }
  switch(col)
  {
   case 0: entrada=0;
       break;
   case 1: entrada=1;
       break;
   case 2: entrada=2;
       break;
   case 3: entrada=3;
       break;
   case 4: entrada=4;
       break;
   case 5: entrada=5;
       break;
   case 6: entrada=6;
       break;
   case 7: entrada=7;
       break;
   case 8: printf("Caracter Incorrecto");
       getch();
       exit(0);
  }
   estado=tabla[estado][entrada];
 if(estado==6)
 {
  printf("Error en la Cadena");
  getch();
  exit(0);
 }
 ind=ind+1;
 }while(estado!=10);
 printf("Cadena Correcta");
 getch();
}

I don't understand why only shows the frist split of the string, and then the variable simbol it converts into NULL.

[Ganon11]

do
 {
  if(simbolo!=NULL)
  {
   simbolo=strtok('\0'," "); // Problem?
   col=evaluar(simbolo);
  }

Maybe because of this statement? Usually, after the first call, strtok is called like

simbolo=strtok(NULL, " ");

Instead, you are using the null character '\0'...maybe some confusion on your part? Try switching '\0' with NULL and see if your output is correct.

[LucasBishop]

No, it gives me the same error; i don't know why but in this part:

 simbolo=strtok(NULL," ");

simbolo aquire the value NULL and then I only obtain the first split of the string. I think there's a trouble in the part where i writes the string, but I don't know why:

 printf("Introduzca la cadena -> ");
             scanf("%s",cadena); //here, when i put a string in this variable just                               obtain the first split,
              do
                {
                 if(simbolo!=NULL)
                 {
                  simbolo=strtok('\0'," ");
                  col=evaluar(simbolo);
                 }

Instead, if i define the variable "cadena" form the begining, it works (like this):

char cadena[80]="el niño";

[Savage]

Have u tryed running it step by step?

It might be that part with !=NULL never gets executed for some reason

Savage

[LucasBishop]

Yes, i've tried, but it doen't work.

[Savage]

Yes, i've tried, but it doen't work.

So those it get executed?

Savage

[LucasBishop]

Yup, but it doesn't give the result that i want; it ggives me just the first split of he string, and the next splits become in NULL's.

[Savage]

I got it:


The problem is in scanf("%s",cadena).U have forgoten &operator in call.Also if problem persist after this use gets() instead and evrything should work

Savage

[LucasBishop]

Jeeeez!!! you have right!!! I've forgetten the operator &, but the really answer was the gets(), THANKS A LOT, DUDE.

[Savage]

Jeeeez!!! you have right!!! I've forgetten the operator &, but the really answer was the gets(), THANKS A LOT, DUDE.

I'm more than happy to help u!!

Main reason why scanf didn't worked is (I think) that it ignores whitespaces and don't put them in array.That way ur pointer will allways point to the same location in string

Savage

[LucasBishop]

Wait, i don't really understood the part when you say, that the pointer will always point to the same location in string. I think you refer to "cadena", right??

[Savage]

Wait, i don't really understood the part when you say, that the pointer will always point to the same location in string. I think you refer to "cadena", right??

Right.When called inside the function strtok() it can be named as a pointer.

Firt call to the function writes a null character just after the returned token.Other calls continue from there but becasue scanf ignored all whitespaces it would allways print out the same part of the string.

Savage

[LucasBishop]

Ok, thats right, thanks!

[Savage]

And again:I'm more than happy to help u!!

Savage