GDB breakpoint on function arguments

Question

Can we set a GDB breakpoint on a function such that it will break into only if the function argument matches the value specified? Ex

int foo(int i) {
return i*i;
}

int main() {
  foo(0);
  ................
  foo(9);
}

How do I set a breakpoint on foo only when the argument i of foo is 5?

blue112 · Accepted Answer · 2014-10-14 09:18:12Z

6

Sure, use "break if"

break foo if i == 5

If you have multiple variable if need to break on, just use classic if syntax :

break foo if i == 5 && j == 3

answered Oct 14, 2014 at 9:18

blue112

57.2k3 gold badges52 silver badges58 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Thanks! what if I have to match multiple arguments in foo(i,j,k) ?

break foo if i == 5 && j == 3, as simply as that.

@kartik: use the syntax familiar from C ... I.e. i == 5 && j == 3 (on occasion it is picky about parentheses being added and how).

@kartik No problem, be sure to validate the answer if it fits your needs.

@blue112 Yes waiting for 5 minute time limit to choose the answer.