Searching a binary file

This is a discussion on Searching a binary file within the C++ Programming forums, part of the General Programming Boards category; I am trying to write a function which searches a binary file for the occurance of a particular string of ...

  1. #1
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    Searching a binary file

    I am trying to write a function which searches a binary file for the occurance of a particular string of characters. I've made some progress but have got a little stuck. Here's what I have come up with so far
    Code:
    void searchRandomObjectForName(string fname)
        
    {
        	int index = 0;
        	string search, name;
        	cout << "Enter a string to search the file for: " << flush;
             cin >> search;
        	ifstream is(fname.c_str(), ios::binary); // open file to read
    
             // while we can read from the file
             while(is.read(reinterpret_cast<char *>(&name), sizeof(int)))
             {
          	    // search here, print out string and position in the file
                // or print "string not found message."
             }
              is.close(); // close file when done
        	cout << endl;
    }
    Can anybody help out?
    Last edited by rhysmeister; 04-18-2004 at 01:56 PM. Reason: code tages / formatting

  2. #2
    and the hat of wrongness Salem's Avatar
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    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  3. #3
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    One solution is strstr().

    Kuphryn

  4. #4
    End Of Line Hammer's Avatar
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    The file is binary, so I guess it'd be safe to assume that strings aren't the best thing to store data in.

    Here's one way of doing what you want
    Code:
     #include <iostream>
     #include <fstream>
     
     int main()
     {  
       char  LookForArray[] = "\x11\x12\x13";
       int   Len = sizeof(LookForArray) - 1;
       int   LookForByte = 0;
       int   c;
       std::ifstream is("myfile.bin", std::ios::binary);
       
       while (LookForByte < Len && (c = is.get()) != EOF)
       {
     	if (c == LookForArray[LookForByte])
     	  LookForByte++;
     	else LookForByte = 0;
       }
       
       if (LookForByte == Len)
       {
     	std::cout <<"item was found" <<std::endl;
       }
       else
       {
     	std::cout <<"item was not found" <<std::endl;
       }
       
       is.close();
     }
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  5. #5
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    Another solution is memchr().

    Kuphryn

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