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Changing the I/O Buffer Size

The following example opens a file named SAMPLE.TXT for unbuffered I/O, and then enables buffered I/O with an internal 16K buffer using the mmioSetBuffer function.

HMMIO hFile; 

if ((hFile = mmioOpen("SAMPLE.TXT", NULL, MMIO_READ)) != NULL) 
    // File opened successfully; request an I/O buffer. 
    if (mmioSetBuffer(hFile, NULL, 16384L, 0)) 
        // Buffer cannot be allocated. 
        // Buffer allocated successfully. 
    // File cannot be opened.