Breakpoints are set with the break command (abbreviated b). The debugger convenience variable '$bpnum' records the number of the breakpoint you have set most recently; see “Convenience variables” (page 96), for a discussion of what you can do with convenience variables.
You have several ways to say where the breakpoint should go.
break function | Set a breakpoint at entry to function function. When |
| using source languages that permit overloading |
| of symbols, such as C++, function may refer to more |
| than one possible place to break. See “Breakpoint |
| menus” (page 62), for a discussion of that |
| situation. |
break +offset, break | Set a breakpoint some number of lines forward or |
back from the position at which execution stopped | |
| in the currently selected stack frame. (See “Stack |
| frames” (page 71), for a description of stack |
| frames.) |
break linenum | Set a breakpoint at line linenum in the current |
| source file. The current source file is the last file |
| whose source text was printed. The breakpoint |
| will stop your program just before it executes any |
| of the code on that line. |
break filename:linenum | Set a breakpoint at line linenum in source file |
| filename. |
break filename:function | Set a breakpoint at entry to function function |
| found in file filename. Specifying a fie name as |
| well as a function name is superfluous except |
| when multiple files contain similarly named |
| functions. |
break *address | Set a breakpoint at address address. You can use |
| this to set breakpoints in parts of your program |
| which do not have debugging information or |
| source files. |
break | When called without any arguments, break sets |
| a breakpoint at the next instruction to be executed |
| in the selected stack frame (see Chapter 6 |
| (page 71)). In any selected frame but the |
| innermost, this makes your program stop as soon |
| as control returns to that frame. This is similar to |
| the effect of a finish command in the frame |
| inside the selected frame―except that finish |
52 Stopping and Continuing