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Hey all , i am new here.
I have a problem with the following code :
I want to put in link[] the html links from the table buf .Code:// buf holds the raw html line
char buf[1000];
// this stores 1 link
char link[1000];
char *start = strstr(buf, "<a href");
start = strchr(start+1, '>')+1;
char *end = strstr(buf, "</a>");
memset(link, 0, 1000);
memcpy(start, link, end-start)
I am doing something wrong , can someone help me
FYI, It doesn't have to be '<a href=' in that order, it could be, '<a name... href=' So your method of extracting links is flawed.
Consider searching for '<a' then finding the first 'href=' from '<a' until a closing '>' It doesn't matter to you if they closed the 'a' tag or not.
Remember there is a lot of invalid HTML, some people use quotes, some people don't. You should be able to handle, ' " and no quotes.
ie:
Consider re-thinking your approach, what exactly are you having problems with?Code:<a href=http://google.com>
<a href='http://google.com'>
<a href="http://google.com">
Also try not to hard code the array size into memset, use sizeof(link) in place of that 1000.
The problem is that even with my implementation i think that something should be in the link table. but the array is full empty . If i could save even a part of the link then i could set up properly the html tags so i get the exact part i want .
I hope to became more clear to what i want to do.
Maybe post a larger section of code? Like when you actually fill 'buf' and such... If it's too large use pastebin or something.
I am doing a get from google search pages and the code is something linke this :
Code://There's code before
while ((read(sockfd,buf , sizeof(buf)-1))) {
clean_buf(buf);
}
void clean_buf(char *buf){
// buf holds the raw html line
char buf[1000];
// this stores 1 link
char link[1000];
char *start = strstr(buf, "<a href");
start = strchr(start+1, '>')+1;
char *end = strstr(buf, "</a>");
memset(link, 0, 1000);
memcpy(start, link, end-start);
printf("%s\n",link); //Here is where i want to print the links
}
If you're not forced to use C then I'd suggest you get on the perl bandwagon for something like this.
Otherwise, you've got a little bit of logic problem, if you get an '<a' in say the 999th spot of that array then you'll have a problem.
* You're not null-terminating the string properly... ie if the link is 1000 characters you'll have a problem
* Links longer than 1000 characters will break your program, not to mention a potential segfault if </a> is more than 1000 characters away from <a href=
Consider:
* Allocating memory for the entire page, ie resize a larger buffer each time you recv() and add 'buf' to it
* Introduce a state-machine and get characters 1-by-1 from the network stream (introduces inefficiency problems)
There are probably a few other ways to go around it.
Note: There are several advantages to Allocating memory for the whole page, those include you could just replace </a> with a NUL terminator and have an array of pointers, pointing to the start of each link (ie href=) or something.
First of all thanks for your interest.
Would it be better to use a struct to save the buf and the links and use DMA for the tables ?
Ps: I have to do it with C , i know that i would be easier and faster with Perl .
Not really, I'd just have a large DMA'd buffer which I resized when I got data from recv(). I'd then append the 'buf' from recv() to the larger DMA'd buffer.
After I had finished recv()'ing the whole page, I'd then scan it for links creating an array of pointers (or a struct with pointers) which point to the links, links which I nul-terminated by replacing '</a>' with '\0'. Then I'd print the links and free the DMA'd buffer.
ie:
DMA buffer before parsing:
And after:Code:<html>
<head>
<title>Google</title>
</head>
<body>
<a href="http://google.com.au/">Google Link</a>
<a href="http://yahoo.com/">Yahoo link</a>
</body>
</html>
Where 0 = NUL-Terminator and P is a pointer, (ie keep the addess in a table, struct, array whatever.)Code:<html>
<head>
<title>Google</title>
</head>
<body>
<a href="Phttp://google.com.au/0>PGoogle Link0/a>
<a href="Phttp://yahoo.com/0>PYahoo link0/a>
</body>
</html>
Then you only have to keep pointers, no more sizing memory or link length limit:
eg:
You could then keep an array of 'links' and DMA / resize it at will.Code:typedef struct link_t {
char * title;
char * url;
} link;
Thanks a lot man for your advise.
I 'll try it right now :P
too bad u have to do it with C ... well
mmm.. javascript:alert(document.links[0]) ... if you could get access this links array from C I think it would be good..
would be amusingly easier in javascript :D.. well it works with client side files... such as if you save the google source to your hard drive.. so you would get local file:// type links
if they use relative pathnames .. if not this should work. of course like person said before if its bad code thats a different story.
Code:<script type="text/javascript">
for (var x=0;x<document.links.length;x++)
document.write(document.links[x]+ "<br />");
</script>