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From: ewing@tortuga.SanDiego.NCR.COM (David Ewing)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Compairing C values
Message-ID: <1991Feb6.211923.2940@SanDiego.NCR.COM>
Date: 6 Feb 91 21:19:23 GMT
References: <rat.3380@hotcity.UUCP> <606.27aede55@vger.nsu.edu>
Sender: @SanDiego.NCR.COM
Reply-To: ewing@tortuga.SanDiego.NCR.COM (David Ewing)
Organization: NCR Corporation, Rancho Bernardo
Lines: 56

Newsgroups: comp.sys.amiga.programmer
Subject: Re: Compairing C values
Summary: also assigning a char * to a char
References: <rat.3380@hotcity.UUCP> <606.27aede55@vger.nsu.edu>
Reply-To: ewing@tortuga.SanDiego.NCR.COM (David Ewing)
Distribution: na
Organization: NCR Corporation, Rancho Bernardo

>> void main(int argc, char *argv[])
>> {
>> char a = argv[1];
>> if (a = '+') printf("a equals +");
...

In addition to the use of the wrong operator as already mentioned
(ie, you used = instead of ==), you are assigning a char pointer to
a char :
  char a = argv[1];
argv is an array of char pointers, therefore argv[1] is a char
pointer, not a char.

This should either be :
  char a = *argv[1]; /* note : dereferencing the pointer */
  if (a == '+') {
     /* do whatever */
  }
if you are only concerned with the first character in the second
string (ie, this will accept "test +anything" as well as just
"test +")  --

or if you only want to accept "+" and not "+anything" :
  char *a = argv[1]; /* note a is now a char * */
  if (a)  { /* be sure argv[1] was not NULL !!! */
     if (strcmp(a, "+") == 0) {
     /* do whatever */
     }
  }

David Ewing
ewing@se-sd.sandiego.ncr.com
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Compairing C values
Summary: 
Expires: 
References: <rat.3380@hotcity.UUCP> <606.27aede55@vger.nsu.edu>
Sender: 
Reply-To: ewing@tortuga.SanDiego.NCR.COM (David Ewing)
Followup-To: 
Distribution: 
Organization: NCR Corporation, Rancho Bernardo
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*********************************************
David A. Ewing
ewing@tortuga.sandiego.ncr.com
*********************************************