The debugger allows you to associate a condition with a breakpoint, so that execution stops only when the line is executed and the condition is met.
To associate a condition with a breakpoint:
From the Source window, select Break→Display. The Breakpoints window is displayed.
In the Breakpoints window, click a breakpoint to select it.
Select Break→Condition. A window is displayed with a field for entering an expression. The execution will stop when the condition is true.
The expressions used here are the same as those that can be used in the Inspection window, and include the following:
Expressions using the dot operator
Expressions using subscripts 
Expressions using parentheses, arithmetic, or logical operators.