Exceptions to implement Program Logic

Sometimes it is conveniant to use exceptions for implementing the regular program logic. Assuming we want to find some data and then process them. When no data is found, this step can be skipped, because there is nothing to do. So we could program something like this: public Data readData(Param param) {     Data data = db.read(param);     if (data.isEmpty()) {         throw new NotFoundException(„nothing found“);     }     return data; } public ProcessedData doWork(Param param) { […]

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Meaningless Whitespace in Textfiles

We use different file formats that are more or less tolerant to certain changes. Most well known is white space in text files. In some programming languages white space (space, newline, carriage return, form feed, tabulator, vertical tab) has no meaning, as long as any whitespace is present. Examples for this are Java, Perl, Lisp […]

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Loops with unknown nesting depth

We often encounter nested loops, like for (i = 0; i < n; i++) { for (j = 0; j < m; j++) { doSomething(i, j); } } This can be nested to a few more levels without too much pain, as long as we observe that the number of iterations for each level need […]

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How to recover the Carry Bit

As frequent readers might have observed, I like the concept of the Carry Bit as it allows for efficient implementations of long integer arithmetic, which I would like to use as default integer type for most application development. And unfortunately such facilities are not available in high level languages like C and Java. But it […]

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