How to extract operand size in bits of a C program? Post: 302978998

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Top Forums Programming How to extract operand size in bits of a C program? Post 302978998 by Don Cragun on Monday 8th of August 2016 03:19:23 AM

08-08-2016

Registered User

OK. That is a different question totally unrelated to the title of this thread. The highest bit set in a non-negative integer number for a number that will fit in a C signed long integer value can be found in a shell that conforms to the POSIX standards using something like:

Code:

printf 'Enter non-negative integer (ctl-D to exit): '
while read -r n
do	printf 'Highest bit set in %s is ' "$n"
	bits=0
	while [ "$n" -gt 0 ]
	do	bits=$((bits + 1))
		n=$((n / 2))
	done
	printf '%d.\n' $bits
	printf 'Enter another non-negative integer (ctl-D to exit): '
done
printf '\nGoodbye\n'

Of course, this doesn't do any validity checking on the values entered and may die a horrible death if a non-numeric entry or an out-of-range numeric entry is given. With a 1993 or later version of the Korn shell, you might be able to process numbers considerably larger than 2**63 - 1.

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LEARN ABOUT OPENDARWIN

type

type(1) 							   User Commands							   type(1)

NAME

       type - write a description of command type

SYNOPSIS

       type name...

DESCRIPTION

       The  type  utility  indicates how each name operand would be interpreted if used as a command. type displays information about each operand
       identifying the operand as a shell built-in, function, alias, hashed command, or keyword, and where applicable, may display  the  operand's
       path name.

       There is also a shell built-in version of type that is similar to the type utility.

OPERANDS

       The following operand is supported:

       name	A name to be interpreted.

ENVIRONMENT VARIABLES

       See  environ(5)	for descriptions of the following environment variables that affect the execution of type: LANG, LC_ALL, LC_CTYPE, LC_MES-
       SAGES, and NLSPATH.

       PATH	Determine the location of name.

EXIT STATUS

       The following exit values are returned:

       0	Successful completion.

       >0	An error occurred.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       typeset(1), attributes(5), environ(5), standards(5)

SunOS 5.10							    1 Feb 1995								   type(1)