Putting Data in a Buffer

2.3 Putting Data in a Buffer

Once you have allocated a buffer, you can put data in it.

In the following listing, a VIEW typed buffer called aud is created with three members (fields). The three members are b_id, the branch identifier taken from the command line (if provided); balance, used to return the requested balance; and ermsg, used to return a message to the status line for the user. When audit is used to request a specific branch balance, the value of the b_id member is set to the branch identifier to which the request is being sent, and the balance and ermsg members are set to zero and the NULL string, respectively.

Listing Putting Data in a Message Buffer - Example 1

... 
audv = (struct aud *)tpalloc("VIEW", "aud", sizeof(struct aud)); 

/* Prepare aud structure */ 

audv->b_id = q_branchid;
audv->balance = 0.0; 
(void)strcpy(audv->ermsg, "");
...

When audit is used to query the total bank balance, the total balance at each site is obtained by a call to the BAL server. To run a query on each site, a representative branch identifier is specified. Representative branch identifiers are stored in an array named sitelist[]. Hence, the aud structure is set up as shown in the following listing.

Listing Placing Data in a Message Buffer - Example 2

... 
/* Prepare aud structure */ 

audv->b_id = sitelist[i];/* routing done on this field */
audv->balance = 0.0; 
(void)strcpy(audv->ermsg, ""); 
...

The process of putting data into a STRING buffer is illustrated in the listing titled “Resizing a Buffer” .