代码片段：生成输入字符串的缩写，只包含字符串中的大写字母。输入字符串仅限于A-Za-z空格、短横线和下划线。

python 实现

import re

def create_abbreviation(phrase):
    """
    生成输入字符串的缩写，只包含字符串中的大写字母。
    输入字符串仅限于A-Za-z空格、短横线和下划线。

    :param phrase: 输入的英文短语或单词。
    :type phrase: str
    :return: 生成的缩写，由输入字符串中的大写字母组成。
    :rtype: str
    """
    allowed_char_reg = r'^[A-Za-z\-\_ ]+$'
    if not re.match(allowed_char_reg, phrase):
        raise ValueError('Input string contains invalid characters.')

    # 初始化一个空字符串来存储缩写
    abbreviation = ''

    # 遍历输入字符串的每个字符
    for char in phrase:
        # 检查当前字符是否为大写字母，并且是否在允许的字符范围内
        if char.isupper():
            # 如果是大写字母，则将其添加到缩写字符串中
            abbreviation += char

    # 返回生成的缩写字符串
    return abbreviation

# 测试示例
print(create_abbreviation("United States"))  # 输出: US
print(create_abbreviation("Structured Query Language"))  # 输出: SQL
print(create_abbreviation("Python Programming Language"))  # 输出: PPL
print(create_abbreviation("PostGreSQL"))  # 输出: PGSQL
print(create_abbreviation("C Sharp Programming Language"))  # 输出: CSPL
print(create_abbreviation("MicroSoft Intermediate Language"))  # 输出: MSIL
print(create_abbreviation("SET if Not eXists"))  # 输出: SETNX
print(create_abbreviation("JavaScript Object Notation"))  # 输出: JSON
print(create_abbreviation("eXtensible Markup Language"))  # 输出: XML
print(create_abbreviation("Asynchronous Javascript And Xml"))  # 输出: AJAX
print(create_abbreviation("HyperText Markup Language"))  # 输出: HTML
print(create_abbreviation("HyperText Transfer Protocol"))  # 输出: HTTP
print(create_abbreviation("Cascading Style Sheets"))  # 输出: CSS
print(create_abbreviation("Document Object Model"))  # 输出: DOM
print(create_abbreviation("File Transfer Protocol"))  # 输出: FTP
print(create_abbreviation("Simple Mail Transfer Protocol"))  # 输出: SMTP
print(create_abbreviation("HyperText Transfer Protocol Secure"))  # 输出: HTTPS

javascript 实现

/**
 * 生成输入字符串的缩写，只包含字符串中的大写字母。
 * 输入字符串仅限于A-Za-z空格、短横线和下划线。
 *
 * @param {string} phrase - 输入的英文短语或单词。
 * @returns {string} - 生成的缩写，由输入字符串中的大写字母组成。
 */
function create_abbreviation(phrase) {
    let allowedCharReg = /^[A-Za-z\-\_ ]+$/;
    if(allowedCharReg.test(phrase) === false) {
        throw new Error('Input string contains invalid characters.');
    }

    // 初始化一个空字符串来存储缩写
    let abbreviation = '';

    // 遍历输入字符串的每个字符
    for (let char of phrase) {
        // 检查当前字符是否为大写字母，并且是否在允许的字符范围内
        if (char === char.toUpperCase() && char !=char.toLowerCase()) {
            // 如果是大写字母，则将其添加到缩写字符串中
            abbreviation += char;
        }
    }

    // 返回生成的缩写字符串
    return abbreviation;
}

// 测试示例
console.log(create_abbreviation("United States"));  // 输出: US
console.log(create_abbreviation("Structured Query Language"));  // 输出: SQL
console.log(create_abbreviation("Python Programming Language"));  // 输出: PPL
console.log(create_abbreviation("PostGreSQL"));  // 输出: PGSQL
console.log(create_abbreviation("C Sharp Programming Language"));  // 输出: CSPL
console.log(create_abbreviation("MicroSoft Intermediate Language"));  // 输出: MSIL
console.log(create_abbreviation("SET if Not eXists"));  // 输出: SETNX
console.log(create_abbreviation("JavaScript Object Notation"));  // 输出: JSON
console.log(create_abbreviation("eXtensible Markup Language"));  // 输出: XML
console.log(create_abbreviation("Asynchronous Javascript And Xml"));  // 输出: AJAX
console.log(create_abbreviation("HyperText Markup Language"));  // 输出: HTML
console.log(create_abbreviation("HyperText Transfer Protocol"))  // 输出: HTTP
console.log(create_abbreviation("Cascading Style Sheets"))  // 输出: CSS
console.log(create_abbreviation("Document Object Model"))  // 输出: DOM
console.log(create_abbreviation("File Transfer Protocol"))  // 输出: FTP
console.log(create_abbreviation("Simple Mail Transfer Protocol"))  // 输出: SMTP
console.log(create_abbreviation("HyperText Transfer Protocol Secure"))  // 输出: HTTPS