linux c++前一行

#include <iostream>
#include <fstream>
#include <string>

std::string getPreviousLine(const std::string& filePath) {
    std::ifstream file(filePath);
    std::string line, previousLine;
    
    while (std::getline(file, line)) {
        if (!previousLine.empty()) {
            // 当前行非空，则前一行就是previousLine
            break;
        }
        previousLine = line; // 更新前一行
    }
    
    file.close();
    return previousLine;
}

int main() {
    std::string filePath = "example.txt";
    std::string previousLine = getPreviousLine(filePath);
    if (!previousLine.empty()) {
        std::cout << "前一行内容是: " << previousLine << std::endl;
    } else {
        std::cout << "文件为空或只有一行。" << std::endl;
    }
    return 0;
}

#include <iostream>
#include <thread>
#include <chrono>

int main() {
    std::cout << "第一行输出" << std::endl;
    std::this_thread::sleep_for(std::chrono::seconds(1)); // 等待1秒
    
    // 使用ANSI转义序列将光标上移一行
    std::cout << "\033[A";
    std::cout << "这是覆盖在前一行上的新输出" << std::endl;
    
    return 0;
}

std::string previousLine;
while (读取新行) {
    if (!previousLine.empty()) {
        // 处理previousLine
    }
    previousLine = 当前行;
}