Dbx 1024 User's Guide download pdf (Page 55)

Displaying and Changing Program Variables

The leading dot is useful when a ﬁle and a procedure have the same name.

For instance, suppose mrx.c contains a function called mrx. Further, suppose

that mrx.c contains a global variable called mi and a local variable, also called

mi. To refer to the global variable, use the qualiﬁed form .mrx.mi, and to refer

to the local variable, use the qualiﬁed form mrx.mrx.mi.

Variable Scope

You can access the value of a variable only while it is in scope. The variable

is in scope only if the block or procedure with which it is associated is active.

After you start your program, whenever your program executes a block or

procedure that contains variables, your program allocates space for those

variables and they “come into scope.” You may access the values of those

variables as long as the block or procedure is active. Once the block or

procedure ends, the space for those variables is deallocated and you may no

longer access their values.

Displaying the Value of a Variable

You can display the value of a program variable using the print,printd,printf,

printo, and printx commands and the pd, po, and px aliases described in

“Printing Expressions” on page 37. For example, to print the value of the

program variable total, enter:

(dbx) print total

235

Theprint command also displays arrays, structures, and other complex data

structures. For example, if message is a character array (a string), dbx prints

the string:

(dbx) print message

"Press <Return> to continue."

As a more complex example, consider a simple linked list stored as an array

of elements, each element consisting of a pointer to the next element and an

integer value. If the array is named list, print the entire array by entering:

(dbx) print array

1 2 ... 50 51 52 53 54 55 56 57 58 59 60 ... 157 158

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Dbx 1024 User's Guide Page 55