\nThe \n“Cool,” you think.\n“That parameter is optional, and I can safely pass \nMy program runs fine if standard output is a console,\nbut if I redirect standard output, then it crashes\non the \nThe crash occurs inside the \nBut you need to read further in the documentation for\n \n A pointer to the variable that receives the number of bytes written\n when using a synchronous hFile<\/I> parameter.\n WriteFile<\/B> sets this value to zero\n before doing any work or error checking.\n Use NULL<\/B> for this parameter if this is an asynchronous operation\n to avoid potentially erroneous results.\n<\/P>\n \n This parameter can be NULL<\/B>\n only when the lpOverlapped<\/I> parameter is not NULL<\/B>.\n<\/P>\n<\/DL>\n<\/BLOCKQUOTE>\n \nThat second paragraph is the catch:\nThe parameter is sometimes optional and sometimes mandatory.\nThe annotation language used in the function head is not\nexpressive enough to say,\n“Sometimes optional, sometimes mandatory,”\nso it chooses the weakest annotation (“optional”)\nso as not to generate false positives when run through\n\nstatic code analysis tools<\/A>.\n<\/P>\n \nWith the benefit of hindsight, the functions probably should have\nbeen split into pairs, one for use with an ReadFile<\/CODE>\nand\nWriteFile<\/CODE>\nfunctions have a parameter called\nlpNumberOfByteRead<\/CODE>,\nwhich is documented as\n<\/P>\n\n __out_opt LPDWORD lpNumberOfBytesRead,\n\/\/ or\n __out_opt LPDWORD lpNumberOfBytesWritten,\n<\/PRE>\n
NULL<\/CODE>.”\n<\/P>\n\n
WriteFile<\/CODE> call.\nI verified that the handle is valid.\n<\/P>\n\nint __cdecl main(int, char **)\n{\n \/\/ error checking removed for expository purposes\n HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);\n WriteFile(hStdOut, “hello”, 5, NULL, NULL);\n return 0;\n}\n<\/PRE>\nWriteFile<\/CODE> function\ntrying to write to a null pointer.\n<\/P>\n<\/BLOCKQUOTE>\nWriteFile<\/CODE>:\n<\/P>\n\n
\n
OVERLAPPED<\/CODE>\nstructure and one without.\nThat way, one version of the function would have a mandatory\nlpNumberOfBytesWritten<\/CODE>\nparameter and no\nlpOverlapped<\/CODE> parameter at all;\nthe other would have a mandatory\nlpOverlapped<\/CODE> parameter and no\nlpNumberOfBytesWritten<\/CODE>\nparameter at all.\n<\/P>\n