Red Hat ENTERPRISE LINUX 4 - DEVELOPER TOOLS GUIDE, Manual

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118 Chapter 14. Using gdb with Different Languages
14.4.1.4. C and C ++ defaults
If you allow gdb to set type and range checking automatically, they both default to
off
whenever the
working language changes to C or C ++ . This happens regardless of whether you or gdb selects the
working language.
If you allow gdb to set the language automatically, it recognizes source files whose names end with
.c
,
.C
, or
.cc
, etc, and when gdb enters code compiled from one of these files, it sets the working
language to C or C ++ . Refer to Section 14.1.3 Having gdb infer the source language , for further
details.
14.4.1.5. C and C ++ type and range checks
By default, when gdb parses C or C ++ expressions, type checking is not used. However, if you turn
type checking on, gdb considers two variables type equivalent if:
•
The two variables are structured and have the same structure, union, or enumerated tag.
•
The two variables have the same type name, or types that have been declared equivalent through
typedef
.
Range checking, if turned on, is done on mathematical operations. Array indices are not checked,
since they are often used to index a pointer that is not itself an array.
14.4.1.6. gdb and C
The
set print union
and
show print union
commands apply to the
union
type. When set to
on
, any
union
that is inside a
struct
or
class
is also printed. Otherwise, it appears as
{...}
.
The
@
operator aids in the debugging of dynamic arrays, formed with pointers and a memory allocation
function. Refer to Section 10.1 Expressions .
14.4.1.7. gdb features for C ++
Some gdb commands are particularly useful with C ++ , and some are designed specifically for use
with C ++ . Here is a summary:
breakpoint menus
When you want a breakpoint in a function whose name is overloaded, gdb breakpoint menus
help you specify which function definition you want. Refer to Section 7.1.8 Breakpoint menus .
rbreak
regex
Setting breakpoints using regular expressions is helpful for setting breakpoints on overloaded
functions that are not members of any special classes. Refer to Section 7.1.1 Setting breakpoints .
catch throw
catch catch
Debug C ++ exception handling using these commands. Refer to Section 7.1.3 Setting catch-
points .