Dictionary Data Structure in C

[Uni Git]

I'm trying to make a dictionary data structure program in C that will basically put a text file (with any amount of lines) into a struct.

The dictionary recognises the first word of a line as a word and the rest of the line as a description for that word - obviously the whole line being an entry into the dictionary.

The text file ends with one line with a full stop and that is when the dictionary stops reading the file.

This is the file so far.
[cpp]
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_WORD_SIZE 40
#define MAX_DESC_SIZE 200

void d_initialise() {
struct dictionary {
char word[MAX_WORD_SIZE];
char desc[MAX_DESC_SIZE];
struct dictionary *next; // next entry
};
}

/** returns true if the file is read */
int d_read_from_file(const char * filename) {
d_initialise();
struct dictionary *dict;

FILE *file = fopen(filename, "r");

char line[MAX_WORD_SIZE + MAX_DESC_SIZE + 1];
char *buffer;
int i=0;

if (file == NULL) {
printf("Error reading file.");
return 0;
} else {
while ((fgets(line, sizeof line, file) != NULL) != ".") {
if ((fscanf(file, "%s %[^\n]", dict->word, dict->desc)) != '\n') {
buffer[i] = dict->next;
i++;
}
}
fclose(file);
}
return 1;
}

/** search dictionary for a word and meaning */
int d_lookup(const char * word, char * desc) {

}
[/cpp]

And this is an example text file:

computer Electronic device for processing data according to instructions
playground Area of outdoor play or recreation
plateau Land area with high, level surface
aardvark Unfriendly, nocturnal mammal native to Africa
.

Compilation errors at the moment:

dictionary.c: In function ‘d_read_from_file’:
dictionary.c:32:57: warning: comparison between pointer and integer [enabled by default]
         while ((fgets(line, sizeof line, file) != NULL) != ".") {
                                                         ^
dictionary.c:33:48: error: dereferencing pointer to incomplete type
             if ((fscanf(file, "%s %[^\n]", dict->word, dict->desc)) != '\n') {
                                                ^
dictionary.c:33:60: error: dereferencing pointer to incomplete type
             if ((fscanf(file, "%s %[^\n]", dict->word, dict->desc)) != '\n') {
                                                            ^
dictionary.c:34:33: error: dereferencing pointer to incomplete type
                 buffer[i] = dict->next;
                                 ^
dictionary.c: At top level:
dictionary.c:54:7: error: expected identifier or ‘(’ before ‘else’
     } else {
       ^
dictionary.c:73:1: error: expected identifier or ‘(’ before ‘}’ token
 }
 ^

Thanks in advance!

[Dienes]

Move your dictionary struct definition out of d_initialise() into the global scope, otherwise d_read_from_file() does not see it.

[Uni Git]

I changed d_read_from_file to this:

[cpp]
int d_read_from_file(const char * filename) {
struct dictionary {
char word[MAX_WORD_SIZE];
char desc[MAX_DESC_SIZE];
struct dictionary *next; // next entry
};
struct dictionary *dict;

FILE *file = fopen(filename, "r");

char line[MAX_WORD_SIZE + MAX_DESC_SIZE + 1];
char *buffer;
int i=0;

if (file == NULL) {
printf("Error reading file.");
return 0;
} else {
while ((fgets(line, sizeof line, file) != ".") {
if ((fscanf(file, "%s %[^\n]", dict->word, dict->desc)) != '\n') {
buffer[i] = dict->next;
i++;
}
}
fclose(file);
}
return 1;
}
[/cpp]

And these errors occur when compiling:

dictionary.c: In function ‘d_read_from_file’:
dictionary.c:36:56: error: expected ‘)’ before ‘{’ token
         while ((fgets(line, sizeof line, file) != ".") {
                                                        ^
dictionary.c:43:5: error: expected expression before ‘}’ token
     }
     ^
dictionary.c: At top level:
dictionary.c:58:7: error: expected identifier or ‘(’ before ‘else’
     } else {
       ^
dictionary.c:77:1: error: expected identifier or ‘(’ before ‘}’ token
 }
 ^

[Alternative Acc]

Well, that error message tells you exactly what's missing.

[editline]20th March 2014[/editline]

Besides, this is not how string comparison works in C:

[cpp]
while ((fgets(line, sizeof line, file) != ".") {
[/cpp]

You are comparing two pointers to char arrays, not the string contents. Additionally, this will never evaluate to true, as one of the pointers points to line - which is stored in the stack, being locally declared - and the other one points to a string somewhere in a read-only memory section. They'll never ever be equal. Use [url=http://www.cplusplus.com/reference/cstring/strcmp/]strcmp()[/url] to compare two strings.

[editline]20th March 2014[/editline]

And last but not least, don't forget to move the struct definition into [i]global scope[/i]. That's where it belongs, not in the body of a function. It needs to go outside.