Thread: Simple file parser

Hi,
I am writing a simple file parser for use in another project (for config file). The trickiest thing seems to be skipping unwanted characters (comments, spaces). It works partly, but after the second line of an inputed file processes only the first three characters.

Code:

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


#define TEXT_FILE "data.txt"


int check_char(char *str, int *pos);


int main()
{
    char buffer[1000];
    char buffer2[1000];
    int position = 0;
    int base = 0;
    FILE *file_ptr = fopen(TEXT_FILE, "r");
    if( file_ptr == NULL ) {
        perror(TEXT_FILE);
        exit(1);
    }
    
    memset(buffer, '\0', sizeof(buffer));
    memset(buffer2, '\0', sizeof(buffer2));
    


    while( fgets(buffer, sizeof(buffer), file_ptr) ) {
        base = 0;
        position = 0;
        printf("Data read: %s\n", buffer);
        while( check_char(&buffer[position], &position) ) {
            buffer2[base] = buffer[position];
            position++;
            base++;
        }
        buffer2[position] = 0;
        printf("Contents: %s\n", buffer2);
    
        memset(buffer, '\0', sizeof(buffer));
        memset(buffer2, '\0', sizeof(buffer2));
    }
    
    fclose(file_ptr);
    return 0;
}


int check_char(char *str, int *pos)
{
    char ch = str[*pos];
    
    switch( ch ) {
        case '#':
            while( ch != '\n' )
            {
                *pos = *pos + 1;
                ch = str[*pos];
                if( ch == '\0' || ch == EOF )
                    return 0;
                printf("%c\n", str[*pos]);
            }
            return 1;
            break;
        case ' ':
            printf("Space\n");
            *pos = *pos + 1;
            return 1;
            break;
        case '\0':
        case EOF:
            printf("NULL or EOF\n");
            return 0;
            break;
        default:
            printf("OK\n");
            return 1;
    }
}

NOTE: Currently I am just trying to process and remove unwanted data, the actual processing of extracted data should be much simpler.

Barney McGrew - thanks for the reply, I normally try to avoid using scanf but at least it works.

std10093 - thanks, honestly didn't realise that. Does it initialise the whole buffer though?

At last, found the solution. Line 25 of my code should instead read:

Code:

while( check_char(buffer, &position) ) {

The function must have been unable to read the full range of the char array with the previous arguments.

I have now completed my parsing program / library (hopefully not too many bugs!), available at:
https://github.com/Joshun/simple-parser

With that finished, I can carry on with the game I was working on...