Thread: Char Array passing help

Hello everyone
Im working on a function that takes a character array and returns the nth word in the array into another array using pointers. But Soooomehow, its not working... sigh...
It would be very much appreciated if someone can tell me what im doing wrong

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char *sbreak(const char *st, char *rst, int y)
{
  int x = 0;
  int rli = 0;
  int n = strlen(st);
  for(int i = 0; i < n; i++)
    {
      printf("%c",st[i]);
    }
  for(int i = 0; i < n; i++)
    {
      if(st[i] == " ")
	{
	  x++;
	  continue;
	}
      if(x == y)
	{
	  rst[rli] = st[i];
	  rli++;
	}
    }
}
      
int main(int argc, char *argv[])
{
  char stbreak[128];
  fgets(stbreak, 100, stdin);
  char rst[128]; //the string that is being written to
  sbreak(stbreak, rst, 2); //2 denotes that the 3rd word will be read
  int a = strlen(rst);
  for(int i = 0; i < a; i++)
    {
      printf("%c",rst[i]);
    }
  return 0;
}

Thanks!
(by the way, im using gcc in emacs to compile)

Compile with warnings, and you'll see some things to fix.

Code:

$ gcc -Wall -std=c99 bar.c
bar.c: In function ‘sbreak’:
bar.c:16: warning: comparison between pointer and integer
bar.c:16: warning: comparison with string literal results in unspecified behavior
bar.c: In function ‘main’:
bar.c:35: error: ‘a’ undeclared (first use in this function)
bar.c:35: error: (Each undeclared identifier is reported only once
bar.c:35: error: for each function it appears in.)
bar.c:38: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘int’

You shouldn't be using continues unless they are necessary, also instead of using strlen you could use just check for the ascii null '\0'. Look at my example for a reference:

Code:

/* Compile with gcc -std=c99 File_Name.c -o File_Name.exe */

#include <stdio.h>

char *Grab_Word(
  const char *String,
  const int  Word_Number
){
  /* Test for a word number less than 1 */
  if(Word_Number < 1)
    return NULL;

  /* Stores the index of the String where the word starts */
  int i = 0;
  
  /* Loop through the unneeded words */
  for(int j = 0;j < Word_Number - 1;j++){
  
    /* If the string is an escape character return NULL -- there were not that
       many number of words in the string */
    if((String[i] < ' ' && String[i] > '\t') || String[i] < '\t')
      return NULL;
      
    /* Loop through the spaces */
    for(;String[i] != '\0' && (String[i] == ' ' || String[i] == '\t');i++);
    
    /* Loop through the characters */
    for(;String[i] != '\0' && String[i] > ' ';i++);
  }
  
  /* All we did already was loop passed the words we didnt want,
     there is still a chance that there is no next word (that the String just 
     has spaces at the end. So we loop through the spaces again (just in case) */
  for(;String[i] != '\0' && (String[i] == ' ' || String[i] == '\t');i++);
  
  /* We test for a null character (again, just in case) */
  if((String[i] < ' ' && String[i] > '\t') || String[i] < '\t')
    return NULL;
  
  /* This can be tricky if you are new to c. What I am doing here is
      getting the pointer of the element i (where the word starts)
      and returning it. I am also explicitly type casing the address
      to type char* for the compiler warnings, but without it is
      is still a pointer to the start of the word */
  return (char *)&String[i];
}

int main(void){
  printf("%s\n", Grab_Word("This is a test. It was a SUCCESS!", 5));
}

EDIT: All my code did was return the char * to the start of the word needed, not exactly what you were looking for. Sorry if I confused you.

What exactly happens when you pass back the pointer, are you just passing back one letter? or the rest of the phrase?

An element of a char array is a char not a string. Using a double quote denotes a string i.e " ", using a single quote denotes a character ' '.

This should fix it:

Code:

 
if (st[i] == ' ')  // this is the line that its having an error with
{
x++;
continue;
}

EDIT: Also, if you want to print a string you can use printf("%s", String) instead of looping through the characters, just make sure your string is null terminated