How to find word in file c++ how to#
How to find word in file c++ code#

*out = std::string_view(&*beginWord, std::distance(beginWord, endWord)) To decide whether a character is a letter or a space, let’s use this following lambda: static auto const isSpace = (char letter) Īuto const beginWord = std::find_if_not(lastExaminedPosition, end(s), isSpace) Īuto const endWord = std::find_if(beginWord, end(s), isSpace)

How to find word in file c++ code#

(As feedback for future articles, do you appreciate having a chance to write the code in an sandbox embedded on the page? How can we improve your user experience regarding this?) Traversing the collection Have a go at implementing the function! You can use this playground that contains some basic tests: The point is to have some feedback on your modifications, and quickly. You can always hack together a function that tests your code and returns a boolean to indicate whether the tests passed or not. It’s great to have a unit testing framework in your projects, such as Catch2 or Gtest for example, but if you want to try out some code in an online sandbox, don’t be stopped if you can’t use a testing framework. Try it with testsĬould you think of a way to implement extractWords? It took me several iterations before getting to a solution here, and what helped the most was having a set of unit tests, to try different solutions and refine the function, with instantaneous feedback about whether it is correct. But for the time being let’s stick to returning void. If you see one, let me know and we’ll see if we can return it from the algorithm. For example, std::partition returns the partition point and std::rotate returns the new position of the element that used to be at the beginning of the collection.īut in our case, I’m not sure there is a particularly interesting position in this collection. Note that some STL algorithms return an OutputIterator, to produce an interesting position in the output collection regarding the algorithm. Void extractWords(std::string const& s, OutputIterator out) So here is what the interface will look like: template This iterator is a template parameter, and it could be anything: the begin of a vector, a back_inserter, an stream_iterator, a smart output iterator… To solve this problem, we will build our function on the model of STL algorithm: by using an output iterator.

Or what if we want to send the output to a stream? Again, an intermediary, potentially large vector isn’t an appealing thought. But what if we want to put the results into a std::set? The idea of creating an intermediary std::vector is not so seducing. But in this case, what is the return type? Should it be a std::vector? That sounds like a reasonable choice. In general, we should strive for functions to output their results via their output types. What should the interface of the function look like? Its input is the string to traverse, and its output is a collection of words. Let’s design the extractWords function, that takes a strings and fishes out among spaces the words it contains.

And before seeing a solution, you will have a chance to code it up yourself! Extracting words as strings

How to find word in file c++ how to#

This is an interesting exercise because it allows to think about how to write expressive code, in particular with good naming and to use STL algorithms. We will do it in two ways: the first one is to output a collection of std::strings, and the other one to output a collection of std::string_views. We’d like to extract 3 sub-strings: “word1”, “word2” and “word3”. We’ve already seen how to split a string into words with a delimiter, but there is another use case that is pretty close, and that doesn’t have the same implementation: extracting words that are among spaces in a string.įor example, from the following string: 'word1 word2 word3 '