Dbx 1024 User's Guide download pdf (Page 60)

Chapter 5: Examining and Changing Data

For example, to display the type declaration for the variable i, enter:

(dbx) whatis i

int i;

The following example illustrates the output of whatis for an array of

structures:

(dbx) whatis array

struct list {

struct list* next;

int value;

} array[12];

When you provide a procedure name to whatis, dbx reports the type of the

value returned by the procedure and the types of all arguments to the

procedure:

(dbx) whatis foo

int foo(i)

int i;

(dbx) whatis main

int main(argc, argv)

int argc;

char** argv;

Examining the Stack

Each time your program executes a procedure, the information about where

in the program the call was made from is saved on a stack. The stack also

contains arguments to the procedure and all of the procedure’s local

variables. Each procedure on the stack deﬁnes an activation level. Activation

levels can also consist of blocks that deﬁne local variables within procedures.

The activation level determines the scope of many dbx commands and

expressions. For example, unless you qualify a variable, as described in

“Qualifying Variable Names” on page 39, dbx assumes that variables you

reference are local to the current activation level.

The most recently called procedure or block is numbered 0. The next active

procedure (the one that called the current procedure) is numbered 1. The last

activation level is always the main program block.

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Dbx 1024 User's Guide Page 60