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POConvert PSTR to PWSTR and Escape Certain Characters
 

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  1. POConvert PSTR to PWSTR and Escape Certain Characters
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    <p>I am trying to put together a function to convert a PSTR to a PWSTR and at the same time, escape certain characters at the same time. I have no control over the input PSTR contains. It can be the contents on any web page.</p> <p>I have the following code already, but I was wondering if there is a better / more effecient way, or if what I have will even work.</p> <pre><code>__inline PCWSTR ToEscape(CHAR c) { switch (c) { case '"': return L"\""; case '\\': return L"\\"; case '\b': return L"\b"; case '\f': return L"\f"; case '\n': return L"\n"; case '\r': return L"\r"; case '\t': return L"\t"; default: return NULL; } } // Helper for mbstowcs_s that does not return NULL terminator included in size __inline DWORD CharToWChar(__out_ecount_opt(cchBuffer) WCHAR* pszBuffer, __in DWORD cchBuffer, __in_ecount(valueLen) PCSTR value, __in DWORD valueLen) { if (valueLen == 0) return 0; size_t dwSize = 0; mbstowcs_s(&amp;dwSize, pszBuffer, cchBuffer, value, valueLen); return dwSize - 1; } // Writes the input value to pszBuffer, or if pszBuffer is NULL, returns the length necessary to write value __inline DWORD WriteJsonValue(__out_ecount_opt(cchBuffer) WCHAR* pszBuffer, __in DWORD cchBuffer, __in PCSTR value) { if (pszBuffer == NULL) { DWORD offset = 2; PCSTR start = value; DWORD index = 0; while (value[index] != '\0') { PCWSTR Escape = ToEscape(value[index]); if (Escape) { offset += CharToWChar(NULL, 0, start, (value + index) - start); start = value + index + 1; offset += 2; } index++; } // Any more left to write? offset += CharToWChar(NULL, 0, start, (value + index) - start); return offset; } else { DWORD offset = 0; if (cchBuffer &lt; 1) return 0; pszBuffer[offset++] = L'"'; PCSTR start = value; DWORD index = 0; while (value[index] != '\0') { PCWSTR Escape = ToEscape(value[index]); if (Escape) { DWORD dwLen = (value + index) - start; offset += CharToWChar(pszBuffer+offset, cchBuffer-offset, start, dwLen); start = value + index + 1; if (cchBuffer &lt; offset + 2) return offset; pszBuffer[offset++] = Escape[0]; pszBuffer[offset++] = Escape[1]; } index++; } // Any more left to write? DWORD dwLen = (value + index) - start; offset += CharToWChar(pszBuffer+offset, cchBuffer-offset, start, dwLen); if (cchBuffer &lt; offset + 1) return offset; pszBuffer[offset++] = L'"'; return offset; } } </code></pre>
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    1. PTQuestion
    1. USNick Banks
    1. USNick Banks
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    1. This table or related slice is empty.
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    1. COWhat's wrong with boost::nowide's "widen()"? (header-only). Or windows mbstowcs()? May I ask you why are you doing it at all? and, http://utf8everywhere.org is a good reference for this kind of tricks.
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      1. POConvert PSTR to PWSTR and Escape Certain Characters
      1. USPavel Radzivilovsky
    2. COI can't use any non Windows APIs. The above was already using mbstowcs_s. The problem wasn't simply converting to wide characters, but efficiently escaping the necessary ones at the same time.
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      1. POConvert PSTR to PWSTR and Escape Certain Characters
      1. USNick Banks
 

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