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Top Forums UNIX for Dummies Questions & Answers defining a variable as a number or character? Post 70207 by noobian on Tuesday 26th of April 2005 06:52:18 PM
Old 04-26-2005
defining a variable as a number or character?

I am writing a script that needs to accept numbers into a variable by prompting and using the code
read num
case $num in
000)
break
;;
*)

I am fairly new to unix and am loving the versatility of the language but need a little shove in the right direction. I know how to define variables in C++, but how do you make sure that a variable is a number? And if a character string is entered instead of a number is there any way that i could send an error message and start the loop again.
thank you in advance
 

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frexp(3M)						  Mathematical Library Functions						 frexp(3M)

NAME
frexp, frexpf, frexpl - extract mantissa and exponent from a floating-point number SYNOPSIS
cc [ flag... ] file... -lm [ library... ] #include <math.h> double frexp(double num, int *exp); float frexpf(float num, int *exp); long double frexpl(long double num, int *exp); DESCRIPTION
These functions break a floating-point number into a normalized fraction and an integral power of 2. They store the integer exponent in the int object pointed to by exp. RETURN VALUES
For finite arguments, these functions return the value x, such that x is a double with magnitude in the interval [1/2, 1) or 0, and num equals x times 2 raised to the power *exp. If num is NaN, NaN is returned and the value of *exp is unspecified. If num is +- 0, +- 0 is returned and the value of *exp is 0. If num is +-Inf, num is returned and the value of *exp is unspecified. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
isnan(3M), ldexp(3M), modf(3M), attributes(5), standards(5) SunOS 5.10 16 Aug 2004 frexp(3M)
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