在许多编程语言中，可以使用变量字符串作为文件名输出。以下是几个示例：

1. Python:

filename = "output.txt"
data = "Hello, World!"

with open(filename, "w") as file:
    file.write(data)

2. JavaScript:

var filename = "output.txt";
var data = "Hello, World!";

var fs = require("fs");
fs.writeFile(filename, data, function(err) {
    if (err) {
        console.log(err);
    } else {
        console.log("File written successfully.");
    }
});

3. Java:

import java.io.FileWriter;
import java.io.IOException;

public class Main {
    public static void main(String[] args) {
        String filename = "output.txt";
        String data = "Hello, World!";
        
        try {
            FileWriter file = new FileWriter(filename);
            file.write(data);
            file.close();
            System.out.println("File written successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

4. C++:

#include 
#include 
using namespace std;

int main() {
    string filename = "output.txt";
    string data = "Hello, World!";
    
    ofstream file;
    file.open(filename);
    if (file.is_open()) {
        file << data;
        file.close();
        cout << "File written successfully." << endl;
    } else {
        cout << "Error opening file." << endl;
    }
    
    return 0;
}

请注意，这些示例仅为了演示目的，实际使用时可能需要添加错误处理和适应特定需求的其他代码。