Tag Archives: correctness

Compile-time string concatenation

We will start with a bug, taken from real life. It spans across three files: Question: what happens when this program is executed? Advertisements

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Asserts in constexpr functions

Assertions (like C-style macro assert) are not an ideal, but still useful tool for indicating assumptions about program correctness, and help finding programmer bugs. In this post we will see how we can use assertions in constexpr functions. This works … Continue reading

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Toggles in functions

Have you ever seen a function call like this? We are processing something: this should be clear from the context. But what do these parameters mean? What is true and what is false? From the function call we will never … Continue reading

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(Not) detecting bugs

The following code contains a bug. A developer has spent quite some time looking for the source. The intent of this code is to iterate over two vectors simultaneously, from the first up to the one-before-last element. Thus the most … Continue reading

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More const — fewer bugs

I have just read article “Please declare your variables as const” by Bartłomiej Filipek. It argues that declaring your variables const is beneficial for reasons other than performance. In particular, it can help find bugs in your code. Now, let … Continue reading

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Concealing bugs

Consider the following piece of program code. This program is expected to open file contents.txt, read names from it; then find a desired name, and do something with it. But the program will not do it, because I have a … Continue reading

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The One-Definition Rule

We have been hit by the same bug twice already this year. It ends in a crash, and it took developers days to find it (in each case), even though it is reproducible on each run of unit tests. The … Continue reading

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