CODEWITHSUNDEEP
c++gdb
sooniln
sooniln

Reputation: 14656

How do I set a breakpoint on operator< with GDB

Basically what the title says. I have a function:

bool operator< (... lhs, ... rhs)

that I would like to break on. 'b operator<(...)' gives me the error:

malformed template specification in command

How can I stop GDB from thinking the < is a template opener? I've tried to set a breakpoint by line number as well, but this definition is in a header file, and for some reason, GDB thinks that line number doesn't exist in the header file.

GDB 6.8

Upvotes: 3

Views: 2592

Answers (2)

Tuxdude
Tuxdude

Reputation: 49583

You could first print all occurrences of operator <, grab the address of the function you're interested and set a breakpoint on it.

NOTE: This technique would work irrespective of your function definition is in .h or .cpp file as long as you have compiled with g++ using -g

$ gdb test

(gdb) p 'operator <'
$1 = {bool (MyClass &, MyClass &)} 0x4009aa <operator<(MyClass&, MyClass&)>

(gdb) b *0x4009aa
Breakpoint 1 at 0x4009aa: file test.h, line 5.

(gdb) r
Starting program: /home/agururaghave/.scratch/gdb-test/test 

Breakpoint 1, operator< (obj1=..., obj2=...) at test.cpp:6
6           friend bool operator < ( MyClass &obj1, MyClass &obj2 ) {

I tested out with the following code:

/* test.h */
#include <iostream>
class MyClass {
public:
    friend bool operator < ( MyClass &obj1, MyClass &obj2 ) {
        std::cout << "operator <" << "\n";  
        return true;
    }
};

/* test.cpp */    
#include "test.h"
int main() {
    MyClass myObj1;
    MyClass myObj2;

    bool result = myObj1 < myObj2;

    std::cout << result << "\n";

    return 0;
}

Upvotes: 7

Jonathan Wakely
Jonathan Wakely

Reputation: 171413

Try putting it in single-quotes:

break 'operator<(Blah, Blah)'

You can also use TAB-completion to get GDB to help you

If that doesn't help you'll need to be more specific about the operator's signature instead of saying "...", since you're omitting the important part of the question!

Oh, I've just seen you're using GDB 6.8 which is about to celebrate its 5th birthday ... upgrade. GDB 7 is much better at parsing C++ declarations.

Upvotes: 2

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