Pointers-general confusion of pointer type.

warny_maelstrom · #1 11-Mar-2004, 12:02

Iv been working on a spellchecker for quite a while and im stucking try to get the program to simply take in one word at a time. Im sure theres a problem with the pointers being of the wrong type or iv written it badly at some point, im now left with the error "ERROR: An expression of type '<ptr>char' cannot not be converted to the function return of type 'int'" its pretty obvious wot the problem is but i just cant seem to solve it. Any help would b welcome.

CPP / C++ / C Code:

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

FILE *ref;
char line[100]; 
char* new_word;
int* pos;
char* split_line(char* line, int* pos);

int main()
        {
        ref = fopen ("reference.txt", "r");
        fgets (line, 100 ,ref);
        while( new_word==split_line(line, pos) )
        printf("%s\n",new_word);
        fclose(ref);
         
        char temp[100];
        char* word;
        int  count = 0;      //Tracks array postion of temp

        while( (*(line + *pos)!=' ')&&(*(line + *pos))!=',')
                {
                temp[count] = *(line + *pos);       //Assign character by character
                count++;
                *pos++;
                printf("%c\n",temp[count]);
                }
        temp[count] = '0';                      //Null terminate the word.
        word = (char*) malloc( strlen(temp) + 1);     //Mallocate just enough room for the word
        strcpy(word,temp);                    //Copy the temporary storage into word
        return(word);
       }

dsmith · #2 11-Mar-2004, 12:15

Hi Warny. It looks like you are trying to get the code working that I gave you. I am on my way out the door, so I didn't look at it too close, but I noticed the biggest problem is that you haven't split out the split_word function. Basically this:

CPP / C++ / C Code:


        while( (*(line + *pos)!=' ')&&(*(line + *pos))!=',')
                {
                temp[count] = *(line + *pos);       //Assign character by character
                count++;
                *pos++;
                printf("%c\n",temp[count]);
                }
        temp[count] = '0';                      //Null terminate the word.
        word = (char*) malloc( strlen(temp) + 1);     //Mallocate just enough room for the word
        strcpy(word,temp);                    //Copy the temporary storage into word
        return(word);

should be included in the split_word function that you make. Right now you have declared it, but it doesn't exist.

I will look at this more later, but I just wanted to clarify that point.

ciao,
d

WaltP · #3 11-Mar-2004, 12:45

Quote:

Originally Posted by warny_maelstrom

Iv been working on a spellchecker for quite a while and im stucking try to get the program to simply take in one word at a time. Im sure theres a problem with the pointers being of the wrong type or iv written it badly at some point, im now left with the error "ERROR: An expression of type '<ptr>char' cannot not be converted to the function return of type 'int'" its pretty obvious wot the problem is but i just cant seem to solve it. Any help would b welcome.

CPP / C++ / C Code:

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

FILE *ref;
char line[100]; 
char* new_word;
int* pos;
char* split_line(char* line, int* pos);

int main()
        {
        ref = fopen ("reference.txt", "r");
        fgets (line, 100 ,ref);
        while( new_word==split_line(line, pos) )
        printf("%s\n",new_word);
        fclose(ref);
         
        char temp[100];
        char* word;
        int  count = 0;      //Tracks array postion of temp

        while( (*(line + *pos)!=' ')&&(*(line + *pos))!=',')
                {
                temp[count] = *(line + *pos);       //Assign character by character
                count++;
                *pos++;
                printf("%c\n",temp[count]);
                }
        temp[count] = '0';                      //Null terminate the word.
        word = (char*) malloc( strlen(temp) + 1);     //Mallocate just enough room for the word
        strcpy(word,temp);                    //Copy the temporary storage into word
        return(word);
       }

Where is the error happening? Place a comment on the line.
Also, comment your code so we know what is happening. What is "reference.txt"? The dictionary? The text to spell check?
split_line() seems to be undefined. And what is the first while loop supposed to do? Just to check the split_line() function?

dsmith · #4 11-Mar-2004, 21:26

Hi Warny.

I have looked over the code and modified it to work. This is a pretty involved procedure and there may be easier and more straight forward ways to do this, but I like using the plain old char class and writing my own low level functions.

Again I urge you to study this and ask questions where you don't understand it. If you just can't understand, post back and see if you can find an alternative solution.

CPP / C++ / C Code:

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

char* split_line(char* line, int* pos)
{
	char	temp[100];
	char*	word;
	int		count = 0;      //Tracks array postion of temp
	
	//Clear whitespace - Need to pass all initial spaces or commas encountered.
	while( ( isspace( *(line+*pos) ) )
			|| ( (*(line + *pos))==',') )
		(*pos)++;
	
	//If after clearing space it is a null return 0
	if(*(line+*pos) == 0) 
		return 0;
	
	
	//Loop and copy string until whitespace or comma.
	while( ( !isspace( *(line+*pos) ) ) && ( (*(line + *pos))!=',') ){
		temp[count] = *(line + *pos);       //Assign character by character
		count++;							//Index temp count position
		(*pos)++;							//Index full line position	
	}
	temp[count] = 0;                      		//Null terminate the word.
	word = (char*) malloc( strlen(temp) + 1);     //Mallocate just enough room for the word
	strcpy(word,temp);                    //Copy the temporary storage into word
	
	return(word);
}



int main()
{
	FILE*	ref;
	char	line[100]; 
	char*	new_word;
	int		pos;
	
	ref = fopen ("split.cpp", "r");
	while(fgets(line, 100 ,ref)){
		printf("line: %s\n",line);
		pos = 0;
		while( new_word=split_line(line, &pos) )
        	printf("\tword: %s\n",new_word);
	}
	
	fclose(ref);
         
	return 0;
}

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