Custom Sort !!
\n# Code\n\nclass Solution {\npublic:\n    string sortVowels(string s, string ret = "") {\n        vector<char>vowels;\n        \n        for(auto &it : s)\n   
\n# Code\n```\nclass Solution {\npublic:\n    string sortVowels(string s, string ret = "") {\n        vector<char>vowels;\n        \n        for(auto &it : s)\n                if((0x208222 >> (it & 0x1f)) & 1) // check vowels in lowercase and uppercase both\n                        vowels.push_back(it);\n        \n        sort(begin(vowels), end(vowels), [](char &a, char &b) {\n            return (int)a < (int)b; // Sort according to their ASCII value\n        });\n        \n        int i = 0;\n        for(char &ch : s){\n            if((0x208222 >> (ch & 0x1f)) & 1)ret += vowels[i++];\n            else ret += ch;\n        }\n        \n        return ret;\n    }\n};\n```\n*Although there is no need of writing custom comparator. Simple sort will work as it will also sort according to ASCII values. Thanks @votrubac Sir for pointing out !*
['C++']