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From: phil@adam.adelaide.edu.au (Phil Kernick)
Newsgroups: comp.sys.amiga.misc
Subject: Re: Compairing C values
Message-ID: <phil.665968010@adam.adelaide.edu.au>
Date: 7 Feb 91 23:06:50 GMT
References: <rat.3380@hotcity.UUCP>
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rat@hotcity.UUCP (P W) writes:


>        I have + as an input arguement via *argv[] and whenever I try to
>compare its value it comes out as a 0.  For instance...  If I compile a
>program like this:

>#include <stdio.h>
>#include <math.h>

>void main(int argc, char *argv[])

>{

>        And I type "test +" (I would name the file test) it would just print a
>equals 0.  Any help would be appereciated...
>char a = argv[1];
>if (a = '+') printf("a equals +");
>if (a = '0') printf("a equals '0'");
>if (a = 0) printf("a equals 0");
>}

Lots of things wrong here.

        1.  This program will not even compile because
                char a = argv[1]; is not a valid declaritor.

        2.  You should check that argv[1] is valid by making sure
            that (argc > 1).  Otherwise (argv[1] == 0) and you do
            *not* want to dereference that.

        3.  argv[1] is a pointer to a pointer to a char, what you
            want is:
                char a;
                a = *argv[1];

        4.  The if (a = ...) statement is an assignment, not a
            comparison.  You need statements like:
                if (a == '+')  printf("a equals +");

        5.  All of the above asside, you *cannot* have a lone '+'
            as a parameter to a program, because AmigaDos eats it.
            See the documentation for the RUN command.


Phil.
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 |     ///    Departmental Engineer     Phone:  +618 228 5914                |
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