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From: thomas@uplog.se (Thomas Hameenaho)
Newsgroups: comp.lang.c
Subject: Re: printf() problem
Message-ID: <THOMAS.89Apr27160452@uplog.uplog.se>
Date: 27 Apr 89 14:04:52 GMT
References: <11657@hodge.UUCP>
Sender: thomas@uplog.UUCP
Organization: TeleLOGIC Uppsala AB
Lines: 26
In-reply-to: jdm@hodge.UUCP's message of 26 Apr 89 00:25:48 GMT

In article <11657@hodge.UUCP> jdm@hodge.UUCP (jdm) writes:
       Perhaps someone could explain this printf() phenomena to me.

       I have a file with binary data.  I want to read four consecutive
       bytes from the file and display them with printf().  The data
       in in the file in hex is:

	   92 AB 4E 33

       I fopen() the file in binary mode and used the following line
       of code to read and print out the data:

	   printf("%x %x %x %x\n", getc(fp), getc(fp), getc(fp), getc(fp));

       printf() displays it as:

	   33 4E AB 92

The problem is that the evaluation order of the arguments to printf (in
this case) is not defined in C. One should NOT have expressions with
sideeffects in function calls. The code will be inherently non-portable.
--
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