What does “ = 0” here mean?

Question

int foo (int a , int b = 0)

I just read this code. I don\'t understand what \" = 0\" means?

I would also like to know why int foo (int a

Answer 1

It sets the default value for the parameter "b" to the function foo, so that the call foo(345) is equivalent to the call foo(345, 0)