基于现有的字符串变量生成字符串变量

let existingString = "Hello";
let newString = `${existingString}, World!`;
console.log(newString); // 输出: Hello, World!

existing_string = "Hello"
new_string = f"{existing_string}, World!"
print(new_string)  # 输出: Hello, World!

String existingString = "Hello";
String newString = String.format("%s, World!", existingString);
System.out.println(newString);  // 输出: Hello, World!

StringBuilder sb = new StringBuilder();
sb.append(existingString);
sb.append(", World!");
String newString = sb.toString();

existing_string = "Hello"
new_string = ''.join([existing_string, ", World!"])
print(new_string)  # 输出: Hello, World!

name = "Alice"
age = 30
# 错误的格式化
message = "My name is %s and I am %d years old." % (name)
print(message)  # 这将引发 TypeError

# 正确的格式化
message = "My name is %s and I am %d years old." % (name, age)
print(message)  # 输出: My name is Alice and I am 30 years old.