C++计算每个字符出现的次数

#include <iostream>//#include <cstdlib>#include <ctime>using namespace std; const int NUMBER_OF_LETTERS = 26;const int NUMBER_OF_RANDOM_LETTERS = 100;void createArray(char []);void displayArray(const char []);void countLetters(const char [], int []);void displayCounts(const int []); int main(){  char chars[NUMBER_OF_RANDOM_LETTERS];  createArray(chars);  cout << "The lowercase letters are:" << endl;  displayArray(chars);  int counts[NUMBER_OF_LETTERS];  countLetters(chars, counts);  cout << "/nThe occurrences of each letter are:" << endl;  displayCounts(counts);   return 0;} void createArray(char chars[]){  srand((unsigned int)time(0));  for (int i = 0; i < NUMBER_OF_RANDOM_LETTERS; i++)  {    chars[i] = static_cast<char>('a' + rand() % ('z' - 'a' + 1));  }} void displayArray(const char chars[]){  for (int i = 0; i < NUMBER_OF_RANDOM_LETTERS; i++)  {    if ((i + 1) % 20 == 0)      cout << chars[i] << " " << endl;    else      cout << chars[i] << " ";  }} void countLetters(const char chars[], int counts[]){  for (int i = 0; i < NUMBER_OF_LETTERS; i++)    counts[i] = 0;  for (int i = 0; i < NUMBER_OF_RANDOM_LETTERS; i++)    counts[chars[i] - 'a']++; //经典} void displayCounts(const int counts[]){  for (int i = 0; i < NUMBER_OF_LETTERS; i++)  {    if ((i + 1) % 10 == 0)      cout << counts[i] << " " << static_cast<char>(i + 'a') << endl;    else      cout << counts[i] << " " << static_cast<char>(i + 'a') << " ";  }  cout << endl;}