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POIn Win32, how can a text file be successfully read into memory?
 

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  1. POIn Win32, how can a text file be successfully read into memory?
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    <p>I am trying to get simple file IO working in Win32. So far the writing is working fine, but the reading is not: although it successfully reads the contents, additional "garbage" is appended to the string. The code I have so far is below. The program has <code>UNICODE</code> defined.</p> <p>For writing:</p> <pre><code>DWORD dwTextSize = GetWindowTextLength(hWndTextBox); WCHAR *lpszText = new WCHAR[dwTextSize]; GetWindowText(hWndTextBox, lpszText, dwTextSize + 1); hTextFile = CreateFile(lpszTextFileName, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); DWORD dwBytesWritten; WriteFile(hTextFile, lpszText, 2 * dwTextSize, &amp;dwBytesWritten, NULL); // x2 for 2 bytes per Unicode character CloseHandle(hTextFile); DeleteObject(hTextFile); </code></pre> <p>For this example, <code>Hello, World!</code> is saved successfully as <code>Hello, World!</code>.</p> <p>For reading:</p> <pre><code>lpszTextFileName = L"text.txt"; // LPCTSTR Variable hTextFile = CreateFile(lpszTextFileName, GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); DWORD dwFileSize = GetFileSize(hTextFile, &amp;dwFileSize); DWORD dwBytesRead; WCHAR *lpszText = new WCHAR[dwFileSize / 2]; ReadFile(hTextFile, lpszText, dwFileSize, &amp;dwBytesRead, NULL); CloseHandle(hTextFile); </code></pre> <p>The string is then used to set the text of an EDIT control:</p> <pre><code>SendMessage(hWndTextBox, WM_SETTEXT, NULL, (LPARAM)lpszText); // SetWindowText() also possible </code></pre> <p>When <code>Hello, World!</code> is read back in, it reads back in as <code>Hello, World!﷽﷽ꮫꮫꮫꮫﻮ</code> or a visual variation upon this, but basically "garbage"!</p> <p>I have probably missed something rather obvious, but I cannot see where! Is there a solution to this problem and if so, what is it?</p>
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    1. USBWHazel
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      1. POIn Win32, how can a text file be successfully read into memory?
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      1. VTUpMod
    1. CONull-terminate the string (and make sure to allocate space for that terminator) before sending it to `SendMessage()`. (And in case it wasn't obvious, delete the buffer when you're done with it). Also, `GetWindowText(hWndTextBox, lpszText, dwTextSize + 1)` into a buffer that is allocated on the previous line to be `dwTextSize` probably isn't a wise idea.
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      1. POIn Win32, how can a text file be successfully read into memory?
      1. USWhozCraig
    2. COHow do I go about null-terminating a string in Win32? Is it simply something like `lpszText[sizeof(lpszText) - 1] = (WCHAR)0; // or '\0'`?
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      1. POIn Win32, how can a text file be successfully read into memory?
      1. USBWHazel
    3. COThat will set the 3rd (or 7th, if compiling 64bit) wchar in your string to 0, which is not what you want. `sizeof(pointer-type-var)` is not the same as `sizeof(array-type-var)`. See the post below for how to terminate your string.
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      1. POIn Win32, how can a text file be successfully read into memory?
      1. USWhozCraig
 

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