Thread: Search through file

I want to make a programm that reads the text file link.txt
and then look for the phrase "video_id="

Imagine the the link.txt is something like this:
dSDJSD723jsd843jsd(#$7dkhs=sd=342video_id=YfDHTDhf d/sds093hjf_dfs';

I want to output the text AFTER video_id
for example the output of the above might be:
YfDHTDhfd/sds093hjf_dfs

BEWARE: without '; of the ending.

How can I make this real C++ programm?

for the real thing the link.txt contains the following:

The link.txt file :

var fullscreenUrl = '/watch_fullscreen?video_id=UHvAXLBMWGI&l=51&t=OEgsT oPDskKBFLkte03dOnia39Rzd63j&sk=7Ayx8rGROMLJrkh6LkX j7AC&fs=1&title=CompizFusion';

I want to isolate:
UHvAXLBMWGI&l=51&t=OEgsToPDskKBFLkte03dOnia39Rzd63 j&sk=7Ayx8rGROMLJrkh6LkXj7AC&fs=1&title=CompizFusi on

Thank my friend.

Unfortunatelly this line error my compiler too...
can you fix this ?

Two issues:
1) stringstream does not appear to have a constructor that takes just a string, or at least gcc reports that iss is not a stringstream object but a function taking a string and returning a stringstream. Changing to

Code:

std::stringstream iss(std::string(buf), std::ios_base::out|std::ios_base::in);

worked wonders.
2) I changed istringstream to stringstream just because I thought it looked weird to read out of a istringstream. It may well work with an istringstream as well.

If the programm is this:

Code:

#include <fstream>
#include <sstream>
#include <string>
#include <iostream>

int main()
{
    std::ifstream fi("link.txt",std::ios::binary);
    const unsigned bfsz = 1024;
    char* buf = new char[bfsz];
    const std::string tag("video_id=");

    while(fi.read(buf,bfsz))
    {
        std::string s(buf);
        std::size_t vipos = s.find(tag);
        if(vipos == std::string::npos)
            continue;

        for(unsigned i = 0; i < (bfsz - vipos+tag.size()); ++i)
            fi.unget();

        fi.read(buf,bfsz);
        std::stringstream iss(std::string(buf), std::ios_base::out|std::ios_base::in);
        std::getline(iss, s, ';'); //this line produces an error on my compiler, but I think it's standard...
        std::cout << "This is the id: " << s << std::endl;
        delete [] buf;
        return 0;
    }

and in the same directory I have the link.txt which is:
panosg89@siduxbox:~/scripts$ cat link.txt

Code:

                var fullscreenUrl = '/watch_fullscreen?fs=1&fexp=52460&plid=AARjhkSgdRDLA7PmAAAAoAQcYQA&iv_storage_server=http%3A%2F%2Fwww.google.com%2Freviews%2Fy%2F&creator=tearbd2&video_id=xC5uEe5OzNQ&l=272&sk=rRLOCm6jr8EoL24c2OEYVJLeztH3gxOUC&fmt_map=34%2F0%2F9%2F0%2F115&t=vjVQa1PpcFMTYcmsyIsJHMSgPFLendWhhpUseGsZwWI%3D&hl=en&cr=US&vq=None&iv_module=http%3A%2F%2Fs.ytimg.com%2Fyt%2Fswf%2Fiv_module-vfl79529.swf&title=WINDOWS VISTA AERO VS LINUX UBUNTU BERYL';

I get output that there IS NOT video_id .. . . . ..

Note that the code above will always print that the tag is not found. The important part is, does it print something up above it?

Now, the answer is probably no, because read will set the failbit even if it read something, if it didn't read the full 1K. So you should probably change that while loop into a do-while loop.

Admittedly, when I did that, it didn't print the actual video_id, because the read failed, because the failbit was still set. So look at this as an idea, and not the solution itself, and we'll all be much happier.

Well all I need is a c++ programa to do the job. To output:

Code:

xC5uEe5OzNQ&l=272&sk=rRLOCm6jr8EoL24c2OEYVJLeztH3gxOUC&fmt_map=34%2F0%2F9%2F0%2F115&t=vjVQa1PpcFMTYcmsyIsJHMSgPFLendWhhpUseGsZwWI%3D&hl=en&cr=US&vq=None&iv_module=http%3A%2F%2Fs.ytimg.com%2Fyt%2Fswf%2Fiv_module-vfl79529.swf&title=WINDOWS VISTA AERO VS LINUX UBUNTU BERYL';

I simply ask: Can you make it ?
because I can't make it cause I do not have the knowledge that you have.

I can make it -- I fixed my stupid error, which was not the fault of failbit but me instead.

I suppose we can discuss further if your company would pay my invoice for your on-the-job training; otherwise you should be able to take the very very very large hints provided here and turn out a working program.

I am not working... I am a student of university...
I am running out of time here because I have to post this to my teacher on Tuesday morning.

I know that you are helping me with your advices but I can't find the free time to study the C++ and I/O files in order to sit down and understand the script. But I will do it sometime in the future definitely.

Anyway... this is a good forum and I think that there will be some others with more open source thoughts to give me the working source code without asking for money.

Thank you guys finally I made it:

Code:

#include <fstream>
#include <sstream>
#include <string>
#include <iostream>
using namespace std;

int main()
{
    char FileName[] = "link.txt";
    ifstream myFile;	//  create object myFile from ifstream class
    myFile.open (FileName, ios::binary );
    char *buffer;
    const string sTag("video_id=");

    //Get Length of file
    int length;
    myFile.seekg (0, ios::end);
    length = myFile.tellg();
    myFile.seekg (0, ios::beg);
    
    // allocate memory
    buffer = new char [length];

    myFile.read(buffer,length); // FileName is stored in buffer pointer
    
        string s(buffer); // Store buffer into a string called s
        size_t vipos = s.find(sTag); // vipos hold the number of chars from start to sTag

        for(unsigned i = 0; i < (length - vipos) ; ++i) // remaining chars = all chars - chars from start to sTag
            myFile.unget(); 		// remove the character

        myFile.read(buffer,length);
        std::stringstream iss(std::string(buffer), std::ios_base::in);
        std::getline(iss, s, '\'');
        std::cout <<s;
        delete [] buffer;
        return 0;


    
    std::cout << '\"' << sTag << "\" not found in file " << FileName << std::endl;
    delete [] buffer; 

}