Thread: Simple Line Parsing

Hi,

I'm one month old in C and am here with a simple query. I want to parse a space delimited line in C and read each word and execute some functions based upon those words. e.g.

Say I've :

I am 27 years old\n

I need to get I, am, 27, years and old in some variables. Also there is a little twist, if I've any numeral, I need it as a numeral and not a string.

Could anyone please write a few lines of code and help me in doing this?

Appreciate your guidance.

Thanks,
Angkar

The best way to learn C is by writing your own code. Some hints:

You can use strchr to find a character in a string (space for example).

You can use strtol to convert part of a string to a number, and to determine whether it successfully converted.

Thanks Dave. And could you please explain what the following line is doing from the "=" till the end?

printf("token[%2d] = \"%*.*s\"\n", i, (int)len, (int)len, token);

Thanks,
Angkar

Also what's the significance of *token in the for loop condition?
Lots of new things to learn.

Thanks,
angKar

But suppose I don't want to print the separated tokens and just want to store them in an array. How to do that? (I mean, what function is an alternative to the %s manipulation you are doing in the printf?)

My printf is showing null ! May be I'm not being clear:

Say I've an i/p as :

1 2 3
1 2 4
2 3 4

separated by spaces and \n s.

Now I use Dave's code as:

Code:

/*s is a single line i/p say 1 2 3 */
while(fgets(s,1000,f)!=NULL) 
  {
      char *token=s;
      char *buffer;
      int i,n;
      
      printf("line %d:\n",++k);
      for(i=0;*token;i++)
      {
        size_t len= strcspn(token,"  \n");
	n = sprintf(buffer,"token[%2d] = %*.*s\n", i, (int)len, (int)len,   token");
	printf ("[%s] is a %d chars string\n",buffer,n);
	token+=len+1 ;
      }
   }

I'm getting buffer as null.Is my syntax correct? Also what I want is after first iteration of while loop buffer should be as buffer[0]=1, buffer[1]=2 and buffer[2]=3.

Thanks,
Angshu

Thanks. But how to solve that?

By allocating space for buffer to point to, using malloc, or by changing buffer to a char array instead of a pointer.