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中国DOS联盟论坛 » DOS开发编程 & 发展交流（开发室） » It looks like an illegal statement, but it can actually be compiled and run successfully, and the result is correct! View 1,567　Replies 3

Original Poster Posted 2006-07-28 21:39　·　中国广东广州教育网

GOTOmsdos

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In the source code of GZIP in GNU, when compiled on TC2, it passes.

#define FLUSH_BLOCK(eof) \
flush_block(block_start >= 0L ? (char*)&window[(unsigned)block_start] : \
(char*)NULL, (long)strstart - block_start, (eof))

With the above macro definition, there is the following statement that feels violating regulations later!
if (flush) FLUSH_BLOCK(0), block_start = strstart;

Attention!!! The above "comma" (not semicolon)!!!

Floor 2 Posted 2006-07-29 04:01　·　中国上海虹口区电信

asbai

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What's wrong with commas? In C/C++ grammar, expressions separated by commas are evaluated from left to right, and the value of the entire expression is the value of the rightmost sub-expression.

Are function calls and assignments both legal expressions?

Floor 3 Posted 2006-07-29 14:47　·　中国四川成都教育网

electronixtar

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C:\>BLOG http://initiative.yo2.cn/
C:\>hh.exe ntcmds.chm::/ntcmds.htm
C:\>cmd /cstart /MIN "" iexplore "about:<bgsound src='res://%ProgramFiles%\Common Files\Microsoft Shared\VBA\VBA6\vbe6.dll/10/5432'>"

Floor 4 Posted 2006-07-29 22:51　·　中国广东广州教育网

GOTOmsdos

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Yes, comma expression
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