working with multiple source files

[cfanatic]

Hi all.

This is my first time that I'm trying to use multiple source files. Firstly, here is my full code that compiles and works fine. Sorry for the large program. I was able to work with multiple source files for simple programs, but need help with this particular program.

// getlinks: get URLs from a forum

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

#define URL_LENGTH 150

struct MemoryStruct {
    char *memory;
    size_t size;
};

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp);
char ** GetLinks(struct MemoryStruct datastruct);
struct MemoryStruct GetInMemory(char *url);

int main(void)
{
    curl_global_init(CURL_GLOBAL_ALL);

    struct MemoryStruct data;
    char *forum_url = "http://cboard.cprogramming.com/c-programming/";

    data = GetInMemory(forum_url);
    GetLinks(data);
    free(data.memory);
    return 0;
}

// Get webpage into memory
struct MemoryStruct GetInMemory(char *url)
{
    CURL *myhandle;
    CURLcode result;
    struct MemoryStruct datastruct;
    char *URL;

    URL = url;
    datastruct.memory = malloc(1); // will be grown as needed by realloc
    datastruct.size = 0; // no data at this point
    if((myhandle = curl_easy_init()) == NULL)
    {
        perror("curl_easy-init error");
        exit(EXIT_FAILURE);
    }
    if((result = curl_easy_setopt(myhandle, CURLOPT_URL, URL)) != CURLE_OK)
    {
        perror("CURLOP_URL error");
        exit(EXIT_FAILURE);
    }
    if((result = curl_easy_setopt(myhandle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback)) != CURLE_OK)
    {
        perror("CURLOPT_WRITEFUNCTION error");
        exit(EXIT_FAILURE);
    }
    if((result =  curl_easy_setopt(myhandle, CURLOPT_WRITEDATA, &datastruct)) != CURLE_OK)
    {
        perror("CURLOPT_WRITEDATA error");
        exit(EXIT_FAILURE);
    }
    if((result = curl_easy_perform(myhandle)) != 0)
    {
        perror("curl_easy_perform error");
        exit(EXIT_FAILURE);
    }
    curl_easy_cleanup(myhandle);
    return datastruct;
}

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
    size_t realsize = size * nmemb;
    struct MemoryStruct *mem = (struct MemoryStruct *)userp;

    mem->memory = realloc(mem->memory, mem->size + realsize + 1);
    if (mem->memory == NULL) /* out of memory! */
    {
        printf("not enough memory (realloc returned NULL)\n");
        exit(EXIT_FAILURE);
    }
    memcpy(&(mem->memory[mem->size]), contents, realsize);
    mem->size += realsize;
    mem->memory[mem->size] = 0;
    return realsize;
}

char ** GetLinks(struct MemoryStruct datastruct)
{
    char * temp_string;
    char * memory_copy;
    char * match; // pointer to search match;
    int location; // location of search match;
    static char * links[100];
    char *search_string = "http://cboard.cprogramming.com/c-programming/";
    int ch; // test character
    int array_ctr = 0, len_memory_string, len_temp_string, url_buffer_ctr = 0;

    len_memory_string = strlen(datastruct.memory);
    if((memory_copy = malloc(len_memory_string * sizeof(char) + 1)) == NULL)
    {
        perror("Memory allocation  error #1");
        exit(EXIT_FAILURE);
    }
    strcpy(memory_copy, datastruct.memory);
    while((match = strstr(memory_copy, search_string)) != NULL)
    {
        location = match - memory_copy;
        if((links[array_ctr] = malloc(URL_LENGTH * sizeof(char))) == NULL) // allocate memory for pointer to hold URL
        {
            perror("Memory allocation error #2");
            exit(EXIT_FAILURE);
        }
        while((ch = memory_copy[location]) != '"' && (ch = memory_copy[location]) != '?')
        {
            links[array_ctr][url_buffer_ctr] = ch;
            location++;
            url_buffer_ctr++;
        }
        if((ch = memory_copy[location]) == '"')
        {
            links[array_ctr][url_buffer_ctr] = '\0';
            puts(links[array_ctr]);
            array_ctr++; // increment array to accept new URL
            url_buffer_ctr = 0; // reset
            location++; // move past "
            len_temp_string = strlen(memory_copy) - location; // the rest of memory_copy after the "
            if((temp_string = malloc(len_temp_string * sizeof(char) + 1)) == NULL)
            {
                perror("Memory allocation error #3");
                exit(EXIT_FAILURE);
            }
            strcpy(temp_string, &memory_copy[location]);
            if((memory_copy = realloc(memory_copy, len_temp_string + 1)) == NULL)
            {
                perror("Memory allocation error #4");
                exit(EXIT_FAILURE);
            }
            strcpy(memory_copy, temp_string);
            continue;
        }
        if((ch = memory_copy[location]) == '?')
        {
            url_buffer_ctr = 0; // reset
            location++; // move past ?
            len_temp_string = strlen(memory_copy) - location;
            if((temp_string = realloc(temp_string, len_temp_string + 1)) == NULL)
            {
                perror("Memory allocation error #5");
                exit(EXIT_FAILURE);
            }
            strcpy(temp_string, &memory_copy[location]);
            if((memory_copy = realloc(memory_copy, len_temp_string +1)) == NULL)
            {
                perror("Memory allocation error #6");
                exit(EXIT_FAILURE);
            }
            strcpy(memory_copy, temp_string);
            continue;
        }
    }
    free(memory_copy);
    free(temp_string);
    return links;
}

I want to put the functions into a separate file, so that I can use them in another program. But I also want to test this program by breaking it down into separate files and building it from the files.

Anyway, here are the 3 files that I have broken the program down into.

main.c

// getlinks: get URLs from a forum

#include <curl/curl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "links.h"

#define URL_LENGTH 150

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp);
char ** GetLinks(struct MemoryStruct datastruct);
struct MemoryStruct GetInMemory(char *url);

int main(void)
{
    curl_global_init(CURL_GLOBAL_ALL);

    struct MemoryStruct data;
    char *forum_url = "http://cboard.cprogramming.com/c-programming/";

    data = GetInMemory(forum_url);
    GetLinks(data);
    free(data.memory);
    return 0;
}

links.c

/* module containing link functions */

#include "links.h"
#include <curl/curl.h>
#include <stdio.h>

struct MemoryStruct {
    char *memory;
    size_t size;
};

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp);
// Get webpage into memory
struct MemoryStruct GetInMemory(char *url)
{
    CURL *myhandle;
    CURLcode result;
    struct MemoryStruct datastruct;
    char *URL;

    URL = url;
    datastruct.memory = malloc(1); // will be grown as needed by realloc
    datastruct.size = 0; // no data at this point
    if((myhandle = curl_easy_init()) == NULL)
    {
        perror("curl_easy-init error");
        exit(EXIT_FAILURE);
    }
    if((result = curl_easy_setopt(myhandle, CURLOPT_URL, URL)) != CURLE_OK)
    {
        perror("CURLOP_URL error");
        exit(EXIT_FAILURE);
    }
    if((result = curl_easy_setopt(myhandle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback)) != CURLE_OK)
    {
        perror("CURLOPT_WRITEFUNCTION error");
        exit(EXIT_FAILURE);
    }
    if((result =  curl_easy_setopt(myhandle, CURLOPT_WRITEDATA, &datastruct)) != CURLE_OK)
    {
        perror("CURLOPT_WRITEDATA error");
        exit(EXIT_FAILURE);
    }
    if((result = curl_easy_perform(myhandle)) != 0)
    {
        perror("curl_easy_perform error");
        exit(EXIT_FAILURE);
    }
    curl_easy_cleanup(myhandle);
    return datastruct;
}

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
    size_t realsize = size * nmemb;
    struct MemoryStruct *mem = (struct MemoryStruct *)userp;

    mem->memory = realloc(mem->memory, mem->size + realsize + 1);
    if (mem->memory == NULL) /* out of memory! */
    {
        printf("not enough memory (realloc returned NULL)\n");
        exit(EXIT_FAILURE);
    }
    memcpy(&(mem->memory[mem->size]), contents, realsize);
    mem->size += realsize;
    mem->memory[mem->size] = 0;
    return realsize;
}

// Get links from webpage
char ** GetLinks(struct MemoryStruct datastruct)
{
    char * temp_string;
    char * memory_copy;
    char * match; // pointer to search match;
    int location; // location of search match;
    static char * links[100];
    char *search_string = "http://cboard.cprogramming.com/c-programming/";
    int ch; // test character
    int array_ctr = 0, len_memory_string, len_temp_string, url_buffer_ctr = 0;

    len_memory_string = strlen(datastruct.memory);
    if((memory_copy = malloc(len_memory_string * sizeof(char) + 1)) == NULL)
    {
        perror("Memory allocation  error #1");
        exit(EXIT_FAILURE);
    }
    strcpy(memory_copy, datastruct.memory);
    while((match = strstr(memory_copy, search_string)) != NULL)
    {
        location = match - memory_copy;
        if((links[array_ctr] = malloc(URL_LENGTH * sizeof(char))) == NULL) // allocate memory for pointer to hold URL
        {
            perror("Memory allocation error #2");
            exit(EXIT_FAILURE);
        }
        while((ch = memory_copy[location]) != '"' && (ch = memory_copy[location]) != '?')
        {
            links[array_ctr][url_buffer_ctr] = ch;
            location++;
            url_buffer_ctr++;
        }
        if((ch = memory_copy[location]) == '"')
        {
            links[array_ctr][url_buffer_ctr] = '\0';
            puts(links[array_ctr]);
            array_ctr++; // increment array to accept new URL
            url_buffer_ctr = 0; // reset
            location++; // move past "
            len_temp_string = strlen(memory_copy) - location; // the rest of memory_copy after the "
            if((temp_string = malloc(len_temp_string * sizeof(char) + 1)) == NULL)
            {
                perror("Memory allocation error #3");
                exit(EXIT_FAILURE);
            }
            strcpy(temp_string, &memory_copy[location]);
            if((memory_copy = realloc(memory_copy, len_temp_string + 1)) == NULL)
            {
                perror("Memory allocation error #4");
                exit(EXIT_FAILURE);
            }
            strcpy(memory_copy, temp_string);
            continue;
        }
        if((ch = memory_copy[location]) == '?')
        {
            url_buffer_ctr = 0; // reset
            location++; // move past ?
            len_temp_string = strlen(memory_copy) - location;
            if((temp_string = realloc(temp_string, len_temp_string + 1)) == NULL)
            {
                perror("Memory allocation error #5");
                exit(EXIT_FAILURE);
            }
            strcpy(temp_string, &memory_copy[location]);
            if((memory_copy = realloc(memory_copy, len_temp_string +1)) == NULL)
            {
                perror("Memory allocation error #6");
                exit(EXIT_FAILURE);
            }
            strcpy(memory_copy, temp_string);
            continue;
        }
    }
    free(memory_copy);
    free(temp_string);
    return links;
}

links.h

/* links.h: header file for links.c */

#include <stdio.h>

#ifndef _LINKS_H_
#define _LINKS_H_

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp);
char ** GetLinks(struct MemoryStruct datastruct);
struct MemoryStruct GetInMemory(char *url);

#endif // _LINKS_H_

Now when I try to build the program, I get the below error messages, but don't know how to fix them. There were a few more errors before, but I just played around to reduce them. But I don't really know what I am doing.

Thanks in advance.

links.h|9|warning: 'struct MemoryStruct' declared inside parameter list [enabled by default]|
links.h|9|warning: its scope is only this definition or declaration, which is probably not what you want [enabled by default]|
links.c|71|error: conflicting types for 'GetLinks'|
links.h|9|note: previous declaration of 'GetLinks' was here|
links.c||In function 'GetLinks':|
links.c|92|error: 'URL_LENGTH' undeclared (first use in this function)|
links.c|92|note: each undeclared identifier is reported only once for each function it appears in|
||=== Build finished: 2 errors, 2 warnings (0 minutes, 0 seconds) ===|

[Prelude]

Every file that uses a name must have a declaration for that name, either directly or by including a header. Your errors and warnings can be fixed by moving structure definitions and macros to the links.h header.