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(Unicode C) Decompress Large Text File in BlocksDecompresses a large text file in blocks, and compares the restored (decompressed) file with the original to make sure it's correct.
#include <C_CkCompressionW.h> #include <C_CkFileAccessW.h> #include <C_CkByteData.h> void ChilkatSample(void) { HCkCompressionW compress; BOOL success; HCkFileAccessW fac; const wchar_t *originalPath; HCkFileAccessW facSrc; HCkFileAccessW facDest; int blockSize; int numBlocks; const wchar_t *restoredPath; const wchar_t *decompressedStr; HCkByteData compressedBytes; int i; BOOL bEqualContents; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. // First, let's compress a text file. // We'll then decompress in blocks, and compare the decompressed with the original file. // Compress a text file: compress = CkCompressionW_Create(); CkCompressionW_putAlgorithm(compress,L"deflate"); success = CkCompressionW_CompressFile(compress,L"qa_data/hamlet.xml",L"qa_data/hamlet_compressed.dat"); if (success != TRUE) { wprintf(L"%s\n",CkCompressionW_lastErrorText(compress)); CkCompressionW_Dispose(compress); return; } fac = CkFileAccessW_Create(); // Examine the uncompressed and compressed sizes: originalPath = L"qa_data/hamlet.xml"; // Note: The FileSize method returns a signed 32-bit integer. If the file is potentially larger than 2GB, call FileSizeStr instead to return // the size of the file as a string, then convert to an integer value. wprintf(L"uncompressed size: %d\n",CkFileAccessW_FileSize(fac,originalPath)); wprintf(L"compressed size: %d\n",CkFileAccessW_FileSize(fac,L"qa_data/hamlet_compressed.dat")); // Decompress in blocks.. facSrc = CkFileAccessW_Create(); facDest = CkFileAccessW_Create(); CkFileAccessW_OpenForRead(facSrc,L"qa_data/hamlet_compressed.dat"); // If we compress in 32K chunks, find out how many blocks there will be. blockSize = 32768; numBlocks = CkFileAccessW_GetNumBlocks(facSrc,blockSize); // Open an output file for the decompressed data. restoredPath = L"qa_output/hamlet_restored.xml"; success = CkFileAccessW_OpenForWrite(facDest,restoredPath); if (success != TRUE) { wprintf(L"%s\n",CkFileAccessW_lastErrorText(facDest)); CkCompressionW_Dispose(compress); CkFileAccessW_Dispose(fac); CkFileAccessW_Dispose(facSrc); CkFileAccessW_Dispose(facDest); return; } compressedBytes = CkByteData_Create(); i = 0; while (i < numBlocks) { success = CkFileAccessW_ReadBlock(facSrc,i,blockSize,compressedBytes); if (i == 0) { decompressedStr = CkCompressionW_beginDecompressString(compress,compressedBytes); } else { decompressedStr = CkCompressionW_moreDecompressString(compress,compressedBytes); } CkFileAccessW_AppendText(facDest,decompressedStr,L"utf-8"); i = i + 1; } // At the very end, flush any remaining content, if any. decompressedStr = CkCompressionW_endDecompressString(compress); CkFileAccessW_AppendText(facDest,decompressedStr,L"utf-8"); CkFileAccessW_FileClose(facSrc); CkFileAccessW_FileClose(facDest); // Examine the size of the restored file. wprintf(L"restored size: %d\n",CkFileAccessW_FileSize(fac,restoredPath)); // Compare the contents of the original with the restored. bEqualContents = CkFileAccessW_FileContentsEqual(fac,restoredPath,originalPath); wprintf(L"Contents Equal: %d\n",bEqualContents); CkCompressionW_Dispose(compress); CkFileAccessW_Dispose(fac); CkFileAccessW_Dispose(facSrc); CkFileAccessW_Dispose(facDest); CkByteData_Dispose(compressedBytes); } |
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