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9 Using GDB with Different Languages
Although programming languages generally have common aspects, they are rarely
expressed in the same manner. For instance, in ANSI C, dereferencing a pointer p is
accomplished by *p, but in Modula-2, it is accomplished by p^. Values can also be
represented (and displayed) differently. Hex numbers in C appear as '0x1ae', while
in Modula-2 they appear as '1AEH'.
Language-specific information is built into GDB for some languages, allowing you to
express operations like the above in the native language of your program, and allowing
GDB to output values in a manner consistent with the syntax of the native language.
The language you use to build expressions is called the working language.
9.1 Switching between source languages
There are two ways to control the working language. You can have GDB set it
automatically, or you can select it manually. You can use the set language command
for either purpose. On startup, GDB sets the default language automatically. The
working language is used to determine how expressions are interpreted, how values
are printed, and so on.
In addition to the working language, every source file that GDB knows about has its
own working language. For some object file formats, the compiler might indicate which
language a particular source file is in. However, most of the time GDB infers the
language from the name of the file. The language of a source file controls whether C++
names are demangled―this way backtrace can show each frame appropriately for
its own language. There is no way to set the language of a source file from within GDB,
but you can set the language associated with a filename extension. See “Displaying the
language” (page 103).
This is a common problem when you use a program, such as cfront or f2c, that
generates C but is written in another language. In that case, make the program use
#line directives in its C output; that way GDB will know the correct language of the
source code of the original program, and will display that source code, not the generated
C code.
9.1.1 List of filename extensions and languages
If a source file name ends in one of the following extensions, then GDB infers that its
language is the one indicated.
'.c'
C source file
'.C',
'.cc',
C++ source file
'.cp',
'.cpp',
9.1 Switching between source languages 101