RE:

Thanks Patrick. Now for the tricky one. I have an external DS which has fields defined in it such as CHAR MSGDTp [40] (The field is actually named MSGDT# however the interface converts the # to p to establish a correct C syntax named field). If I want to append some other string via strcpy then both fields have to be a string (according to the manual). Does this mean that I have to convert my external DS field into a string (via a locally define variable, of the same size as the MSGTp field plus 1 )?by appending a null character? And if so how do I do that? Do I have to get complicated by finding the first blank in MSGDT ( or the first non-blank from right to left, plus 1  )and then placing the null (0x00) value into that character position to turn it into a string?

-----Original Message-----
From:   Patrick Townsend [mailto:townsend@patownsend.com]
Sent:   Wednesday, 21 June 2000 14:38
To:     C400-L@midrange.com; 'C400-L@midrange.com'
Subject:        Re:

Mike,

char   mychar;        /* this defines a single character, not a string */
char   mystring[6];   /* this defines a string of 6 bytes. it contains
garbage */
                       /* until you initialize it */

How to compare a character (note the use of single quote):

       if (mychar == '1')
         foo();

How to compare a string (note the use of double quote):

       if (!strcmp(mystring, "hello"))
         foo();

There are other string comparisons. strncmp() compares strings for a given
number of bytes. stricmp() ignores case on the compare, etc.

If you want to check the value of a single character in a string you can do:

       if (mystring[4] == '1')
          foo();

This checks the fifth position in the string for the character value of '1'.

Strings are not null terminated until you make them so. Some C functions
will automatically terminate a string with a null. Some examples:

     memset(mystring, 0, sizeof(mystring));    /* sets the entire string to
nulls */
     strcpy(mystring, "hello");                /* creates a null terminated
string */




Patrick

At 09:03 PM 6/20/2000 -0400, Pantzopoulos, Mike wrote:

>I'm a bit confused about how to deal with a single character. Is a char
>x[1]; or char x; statement defining a string or a character?
>
>Ishould it be compared via a ............if(x== '1')  statement or should
>a strcmp function be invoked? I presume that any definition such as char
>x[6] defines a string (as null terminated). So is char x[1] defining a
>null terminated string of length 2 (inclusive of the null character)?
>

---
IBM AS/400 communications, FTP automation, and network security
software and consulting services.

http://www.patownsend.com

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