What is a breakpoint?
In programming, a breakpoint, as the name suggests, is the point at which a program purposely halts its execution prematurely. It is particularly useful when debugging specific sections of a code or functions of a program.
If you wish to learn more about this concept, check out the FAQ section below:
Question #1: What is a breakpoint for?
As we have seen earlier, a breakpoint is essentially just a marker that tells a program to stop running before its natural termination point. It can be placed virtually anywhere in the code or stage of a program’s execution.
But how exactly is it useful for debugging?
Well, breakpoints are not actually that important when you are debugging extremely simple programs. If something goes wrong, it is very easy to manually scan each line to find what is causing the problem.
An example of this would be a simple web page that displays the message ‘Hello, World!’, which is built using the following lines of code:
<html>
<head>
</head>
<body>
<h1>Hello, World!<h1>
</body>
</html>
As you can see, it should not take you more than a couple of seconds to go through each line, and since the code as a whole is also extremely simple, you should be able to easily spot any errors as well.
For something more complex, such as a messaging app, however, manually scanning the code for errors can be significantly more challenging.
Take Skype, for example. Aside from sending and receiving chat messages, it also allows you to:
- Send and receive files
- Do video calls
- Share your screen
- Record your calls
Now imagine each of these features as a separate section of a very long and extremely complex code. If you had a problem with the video calls section, for example, using a breakpoint (or several breakpoints) would allow you to only run that specific section as many times as you want to test the changes you make instead of running the entire program every time.
Question #2: What is the difference between a software and hardware breakpoint?
There are two main differences between a software and hardware breakpoint:
- How they work
- How many of them you can set up at a given time
Let us take a look at each one in more detail:
First, a software and hardware breakpoint work differently in that the former, as the name suggests, directly modifies the code (i.e., the software) to halt a program while the latter relies on the hardware to perform the same task.
Second, since software breakpoints happen at the code level, you can theoretically have as many of them as you need. The only limit is the maximum number of breakpoints your debugger can read. In contrast, you can only have as many hardware breakpoints as your hardware would allow—which is typically no more than four at a time.
Question #3: Can I debug without using a breakpoint?
In theory, yes, you can debug without using a breakpoint. In fact, as we have seen earlier, you do not really need breakpoints for extremely simple programs with very few components.
However, debugging ultra complex programs with long lines of code can be extremely time-consuming if you do not use breakpoints. Every time you make adjustments to the code and try to test if they work, you will have to either wait for the entire program to finish executing or wait for an error to cause it to prematurely halt its operation.
Question #4: What is the difference between a breakpoint and a watchpoint?
The main difference between a breakpoint and a watchpoint is how they halt the operation of a program. While the former simply marks where the program is supposed to stop, the latter watches a variable and executes the stop command only when that variable reaches a predetermined value.