C++ 计算字母在单词中出现的概率

#include <iostream>
#include <string>
#include <iomanip>
using namespace std;

int main() {
    string letter, word;
    while (cin >> letter >> word) {
        // 将字母和单词都转换为小写字母
        for (int i = 0; i < letter.length(); i++) {
            letter[i] = tolower(letter[i]);
        }
        for (int i = 0; i < word.length(); i++) {
            word[i] = tolower(word[i]);
        }
        
        int count = 0;
        for (int i = 0; i < word.length(); i++) {
            if (word[i] == letter[0]) {
                count++;
            }
        }
        
        double probability = (double)count / word.length();
        cout << fixed << setprecision(5) << probability << endl;
    }
    
    return 0;
}