检查变量中是否存在特定值

# 检查字符串中是否包含子串
variable = "Hello, world!"
substring = "world"
if substring in variable:
    print("Substring found!")
else:
    print("Substring not found.")

// 检查数组中是否存在特定元素
let array = [1, 2, 3, 4, 5];
let value = 3;
if (array.includes(value)) {
    console.log("Value found in array!");
} else {
    console.log("Value not found in array.");
}

// 检查列表中是否存在特定元素
import java.util.List;
import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
        int value = 3;
        if (list.contains(value)) {
            System.out.println("Value found in list!");
        } else {
            System.out.println("Value not found in list.");
        }
    }
}

variable = ""
substring = "world"
if variable and substring in variable:
    print("Substring found!")
else:
    print("Substring not found or variable is empty.")