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    Length: 3064 (0xbf8)
    Types: TextFile
    Names: »number.c«

└─⟦87ddcff64⟧ Bits:30001253 CPHDIST85 Tape, 1985 Autumn Conference Copenhagen
    └─ ⟦this⟧ »cph85dist/stat/src/number.c« 

TextFile

/* Copyright (c) 1982 Gary Perlman (see Copyright file) */

/*
	number: report if a string is a UNIX formatted number

	usage:
		number (string) char *string;

	notes:
		a number in UNIX is one that can be converted from
		a string to an integer or real with no loss of information
			due to bad format
		all numbers can be surrounded by whitespace
		an integer has an optional minus sign, followed by digits
			(a decimal point optinally followed by zeros is forbidden)
		a real number has an optional minus sign followed by didits

	parameters:
		char *string; string is tested to see if it is a number

	side effects:
		none

	value:
		1 is string is an integer [-] 0-9+
		2 is string is a real number
		0 for non-numbers

	compilation flags:
		-DSTANDALONE	includes test main program
	
	trace flags:
		none
	
	deficiencies:
		does not allow optional plus sign because atof(3) does not

		does not check to see if significant digits will be ignored
	
	author:
		Gary Perlman

	date:
		Wed May 22 13:30:40 EDT 1985
		
*/
#include <ctype.h>
static char sccsfid[] = "@(#) number.c 5.1 (unix|stat) 6/15/85";

#define	IS_NOT      0
#define	IS_INT      1
#define	IS_REAL     2

/*LINTLIBRARY*/
number (string)
char	*string;                 /* the string to be tested */
	{
	int 	answer = IS_INT;     /* start by assuming it is an integer */
	int 	before = 0;          /* anything before the decimal? */
	int 	after = 0;           /* anything after the decimal? */
	while (isspace (*string))    /* skip over blank space */
		string++;
	if (!*string)                /* empty string not allowed */
		return (IS_NOT);
	if (*string == '-')          /* optional plus not allowed by atof */
		{
		string++;
		if (!isdigit (*string) && *string != '.') return (IS_NOT);
		}
	if (isdigit (*string))       /* note that there was a digit before . */
		{
		before = 1;
		while (isdigit (*string))
			string++;
		}
	if (*string == '.')          /* found a decimal point, parse for real */
		{
		answer = IS_REAL;
		string++;
		if (isdigit (*string))   /* note that there was a digit after . */
			{
			after = 1;
			while (isdigit (*string))
				string++;
			}
		}
	if (!before && !after)       /* must be digit before or after . */
		return (IS_NOT);
	if (*string == 'E' || *string == 'e') /* exponent */
		{
		answer = IS_REAL;
		string++;
		if (*string == '+' || *string == '-') /* optional sign */
			string++;
		if (!isdigit (*string))  /* missing exponent */
			return (IS_NOT);
		while (isdigit (*string))
			string++;
		}
	while (isspace (*string))    /* skip optional spaces */
		string++;
	/* should now have exhausted the input string */
	return (*string == '\0' ? answer : IS_NOT);
	}

#ifdef STANDALONE

#include <stdio.h>
main ()
	{
	char	line[BUFSIZ];
	while (gets (line))
	puts ("Type in strings and I'll tell you if they are numbers");
		{
		switch (number (line))
			{
			case IS_NOT:
				puts ("	is not a number");
				break;
			case IS_INT:
				puts ("	is an integer");
				break;
			case IS_REAL:
				puts ("	is a real number");
				break;
			}
		}
	}

#endif