TotalView Users Guide - CI Wiki

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Evaluating
Expressions
17
Whether you realize it or not, you’ve been telling TotalView to evaluate
expressions and you’ve even been entering them. In every programming
language, variables are actually expressions—actually
they are lvalues—whose evaluation ends with the interpretation of
memory locations into a displayable value. Structure, pointer and
array variables, particularly arrays where the index is also a variable,
are slightly more complicated.
While debugging, you also need to evaluate expressions that contain
function calls and programming language elements such as for and
while loops.
This chapter discusses what you can do evaluating expressions
within TotalView. The topics discussed are:
� “Why is There an Expression System?” on page 381
� “Using Programming Language Elements” on page 385
� “Using the Evaluate Window” on page 389
� “Using Built-in Variables and Statements” on page 394
Why is There an Expression System?
Either directly or indirectly, accessing and manipulating data requires an
evaluation system. When your program (and TotalView, of course) accesses
data, it must determine where this data resides. The simplest data lookups
involves two operations: looking up an address in your program’s symbol
table and interpreting the information located at this address based on a
variable’s datatype. For simple variables such as an integer or a floating
point number, this is all pretty straightforward.
TotalView Users Guide: version 8.7 381