Adding Break Points157
As you can see from the above lines, when you set a break point, GNU debugger will dis-
play its information in the next line. This information contains the number of the breakpoint,
memory address, file name and line number. You can also see a list of currently set break points
using the following command:
(gdb) info break
Num Type Disp Enb Address What
1 breakpoint keep y 0x08048496 in main at sum.c:6
(gdb)
Break points can also be set on function names. The following command sets a break point
where function
main
starts:
(gdb) break main
Breakpoint 1 at 0x8048496: file sum.c, line 6.
(gdb)
Note that although the function
main()
starts at line number 2, the break point is set at
line number 6. This is because the first executable instruction of the function
main
is located at
this line number.
You can also set a break point at a particular line number in the currently loaded file. The
following command creates a break point at line number 8:
(gdb) break 8
Breakpoint 2 at 0x80484ba: file sum.c, line 8.
(gdb)
In a multi-source file project, you set up a break point by including the file name and line
number on the command line. The following command sets up a break point at line number 9 in
file
sum.c
.
(gdb) break sum.c:9
Breakpoint 3 at 0x80484ca: file sum.c, line 9.
(gdb)
You can also use an offset value to set up a break point. For example if the execution
pointer is on line number 6, you can set up a break point at line number 9 using the following
command. Note that you can also use a minus symbol to specify an offset.
6 printf("Enter first number : ");
(gdb) break +3
Note: breakpoint 3 also set at pc 0x80484ca.
Breakpoint 4 at 0x80484ca: file sum.c, line 9.
(gdb)
All break points can be displayed using the
info
command. The following command dis-
plays three break points that we have specified:
(gdb) info break
Num Type Disp Enb Address What