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9-regular-expressions/13-regexp-alternation/01-find-programming-language/solution.md

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+
+The first idea can be to list the languages with `|` in-between.
+
+But that doesn't work right:
+
+```js run
+let reg = /Java|JavaScript|PHP|C|C\+\+/g;
+
+let str = "Java, JavaScript, PHP, C, C++";
+
+alert( str.match(reg) ); // Java,Java,PHP,C,C
+```
+
+The regular expression engine looks for alternations one-by-one. That is: first it checks if we have  `match:Java`, otherwise -- looks for `match:JavaScript` and so on.
+
+As a result, `match:JavaScript` can never be found, just because `match:Java` is checked first.
+
+The same with `match:C` and `match:C++`.
+
+There are two solutions for that problem:
+
+1. Change the order to check the longer match first: `pattern:JavaScript|Java|C\+\+|C|PHP`.
+2. Merge variants with the same start: `pattern:Java(Script)?|C(\+\+)?|PHP`.
+
+In action:
+
+```js run
+let reg = /Java(Script)?|C(\+\+)?|PHP/g;
+
+let str = "Java, JavaScript, PHP, C, C++";
+
+alert( str.match(reg) ); // Java,JavaScript,PHP,C,C++
+```

9-regular-expressions/13-regexp-alternation/01-find-programming-language/task.md

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+# Find programming languages
+
+There are many programming languages, for instance Java, JavaScript, PHP, C, C++.
+
+Create a regexp that finds them in the string `subject:Java JavaScript PHP C++ C`:
+
+```js
+let reg = /your regexp/g;
+
+alert("Java JavaScript PHP C++ C".match(reg)); // Java JavaScript PHP C++ C
+```