C++实现字母大小写转换

#include <iostream>

int main() {
    char word;
    std::cout << "请输入您的 char:>>>";
    std::cin >> word;
    std::cout << "您的 Word:>>>" << word << std::endl;
    int a = word;
    char pre_word = a - 1;
    char next_word = a + 1;
    char upper_word = a - 32;
    std::cout << "上一个单词:" << pre_word << std::endl;
    std::cout << "下一个单词:" << next_word << std::endl;
    std::cout << "大写:" << upper_word << std::endl;
    return 0;
}