reading in a variable number of long ints on one line using strchr and strtol

Question

My function is not quite done yet, but what I'm going to do is:

• To read in a string of numbers separated by spaces.
• Extract the numbers from that string.
• Convert them to long ints.

• Return the number of numbers read in.

   int input( int a, int b, long int *result_array ) { int ele = 0; char buffer[200]; char *start, *end; scanf("%[^\\n]%*c", buffer ); start = buffer; while( ( end = ( strchr( start, ' ' ) ) != NULL ) ) { result_array = strtol( start, &end, 10 ); ele += 1; start = end + 1; } return ele; } 

It doesn't seem to work properly, I think I'm using strchr wrong.

Answer 1

strtol() returns:

On success, the function returns the converted integral number as a long int value. If no valid conversion could be performed, a zero value is returned (0L).

you should re write your code as:

end = buffer;
base = 10;
long int = li;
ele = 0;
while(li=strtol (end,&end, base)){
     ele += 1;
}
return ele;

You don't need to explicitly use strstr() to locate for next integer. strtol() smart enough and after each conversion it locate end point to next int.

I have written an running code may be your find helpful:

#include <stdio.h>      /* printf */
#include <stdlib.h>     /* strtol */
int main (){
  char buffer[] = "2001 11 223   444   566";
  char * end;
  long int li;
  end =buffer;
  int base =10;
  int ele = 0;
  while(li=strtol (end, &end, base)){
     printf("%ld \n", li);
     ele += 1;
  }
  printf("\nNo of elements: %d", ele);
  return 0;
}

its output:

2001 
11 
223 
444 
566 

No of elements: 5

Link to codepad