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POAccess violations on string operations in Delphi
 

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    <p>I have a Delphi application that reads data form a file and stores it in an array. Each row in a file contains an address, lineTypeIndicator and data. This is the algorithm (contains code that I believe is critical):</p> <pre><code>AssignFile(inputFile, inFileName); Reset(inputFile); while not EOF(inputFile) do begin Readln(inputFile,fileLineBuffer); if Copy(fileLineBuffer, 8, 2) = '01' then //Never managed to catch the error here begin break; end; //extract the address from the line and use it to determine max and min address. end; //Now that you have min and max address, use it to set the length of an char array SetLength(memoryArray,(lastAddress - firstAddress) * 2); Reset(inputFile); while not EOF(inputFile) do begin Readln(inputFile,fileLineBuffer); if Copy(fileLineBuffer, 8, 2) = '01' then //I caught all the errors here begin break; end; //extract the address and data from the fileLineBuffer and place it in the corresponding place in an array end; </code></pre> <p>This code is executed every time the user clicks the corresponding button on a form. It runs the first few times it is executed, but then after a few runs i get this:</p> <blockquote> <p>MyProgram.exe faulted with message: 'access violation at 0x00406111: write of address 0x00090d1c (this varies). Proceess stopped. Use step or run to continue.</p> </blockquote> <p>To me, this smells like some kind of heap overflow. I have tried replacing </p> <pre><code>if Copy(fileLineBuffer, 8, 2) = '01' then </code></pre> <p>with</p> <pre><code>lineTypeBuffer := Copy(fileLineBuffer, 8, 2); if lineTypeBuffer = '01' then </code></pre> <p>or</p> <pre><code>if (fileLineBuffer[8] = '0') and (fileLineBuffer[9] = '1') then </code></pre> <p>but it did not help. Any suggestions on how I should approach this problem?</p> <p>P.S. Tried running it on Win7 32 bit and Win7 64 bit - no difference P.P.S. sorry for the long question.</p>
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