[TUHS] origins of void* -- Apology!

Nelson H. F. Beebe beebe at math.utah.edu
Wed Nov 8 01:34:46 AEST 2017


Arthur Krewat <krewat at kilonet.net> writes on Mon, 6 Nov 2017 19:34:34 -0500

>> char (at least these days) is signed. So really, it's 7-bit ASCII.

I decided last night to investigate that statement, and updated my
C/C++ features tool to test the sign and range of char and wchar_t.  

I ran it in our test lab with physical and virtual machines
representing many different GNU/Hurd, GNU/Linux, *BSD, macOS, Minix,
Solaris, and other Unix family members, on ARM, MIPS, PowerPC, SPARC,
x86, and x86-64 CPU architectures.  Here is a summary:

	% cat *.log | grep '^ char type is' | sort | uniq -c
	    157         char type is          signed
	      3         char type is          unsigned

The sole outliers are 

	* Arch Linux ARM on armv7l
	* IBM CentOS Linux release 7.4.1708 on PowerPC-8
	* SGI IRIX 6.5 on MIPS R10000-SC

for which I found these log data:

	Character range and sign...
		CHAR_MIN                        =   +0
		CHAR_MAX                        = +255
		SCHAR_MIN                       = -128
		SCHAR_MAX                       = +127
		UCHAR_MAX                       = +255
		char type is          unsigned
		signed char type is   signed
		unsigned char type is unsigned

The last two lines are expected, but my program checked for an
incorrect result, and would have produced the string "WRONG!" in the
output; no system had that result.

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