#include #include /* Function charFreqCounter Description: A function to count character frequency in a string. Parameters: string A word or a sentence, number bool [Optional] case sensitivity option, concerned only for alphabets Return value: None (void) NOTE: The function only counts alphanumeric characters, taking account character case for the alphabets. @Ipang © 2017 SoloLearn Community */ void charFreqCounter( std::string buffer, bool ignoreCase = false) { // No blanks allowed if(buffer.empty()) return; // Character frequency counter array: // 26 for each A..Z and a..z // 10 for digits (0..9) int *counter = new int[62]; // Initialize all counter to zero for(int i = 0; i < 62; counter[i] = 0, i++); unsigned int cc, idx; int Mfi {-1}, Mfc {0}; for(char ch : buffer) { // Since we only do alphanums, we use // isalpha and isdigit to know whether if // current character should be included. idx = 0; cc = std::isalpha(ch); if(cc) { // For alphabetical characters; // when = true we'll // just increment the counter for // lowercase letters despite of // the actual char case. if(cc & 1) { if(ignoreCase) idx = ch - 39; else idx = ch - 65; } else idx = ch - 71; } else { if(std::isdigit(ch)) idx = ch + 4; } // Check for most frequent character if(idx) { counter[idx]++; if(counter[idx] > Mfc) { Mfc = counter[idx]; Mfi = idx; } } } char ch; // Display most frequent character ch = Mfi > 51 ? char(Mfi - 4) : Mfi > 25 ? char(Mfi + 71) : char(Mfi + 65); std::cout << "Most frequent character: '" << ch << "'.\nTotal frequency: " << Mfc << " times\n\n"; // Display frequency statistics int i {ignoreCase ? 26 : 0}; idx = 0; for(; i < 62; i++) { if(counter[i]) { // Transform index to respective // character if(i > 51) ch = char(i - 4); // digits else if(i > 25) ch = char(i + 71); // a..z else ch = char(i + 65); // A..Z std::cout << "'" << ch << "' frequency: " << counter[i]; (idx & 1) && std::cout << "\n" || std::cout << ". "; idx++; } } delete [] counter; counter = nullptr; } // Main procedure int main() { std::string buffer; // {"ABBCCCDDDDEEEEE012233344445555566666677777788888888999999999abbcccddddeeeee"}; // Read on until there's nothing left to do. std::cout << "Enter numbers, words or sentences:\n"; while(true) { std::getline(std::cin, buffer); if(!std::cin.good()) break; if(buffer.empty()) continue; std::cout << buffer << "\n\n"; charFreqCounter(buffer); } std::cout << std::endl; return 0; }

Challenge - Character frequency counter