This code takes in various brace styles and converts them to One True Brace Style:
const auto input = "if (KnR)\\n\\tfoo();\\nif (spaces) {\\n foo();\\n}\\nif (allman)\\n{\\n\\tfoo();\\n}\\nif (horstmann)\\n{\\tfoo();\\n}\\nif (pico)\\n{\\tfoo(); }\\nif (whitesmiths)\\n\\t{\\n\\tfoo();\\n\\t}\\n"s;
cout << input << regex_replace(input, regex("(.+?)\\\\s*\\\\{?\\\\s*(.+?;)\\\\s*\\\\}?\\\\s*"), "$1 {\\n\\t$2\\n}\\n") << endl;