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  • c# 替换原有文件内容

    //实现替换原有文件内容
    //Seek(0, SeekOrigin.Begin)将指针指向文件的开始,才能从文件的开头,但是此时如果新写入的流长度小于原有文件长度,则会保留原文件多余的信息
    using (FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Write, FileShare.Write))
    {
        fileStream.Seek(0, SeekOrigin.Begin);
        using (StreamWriter streamWriter = new StreamWriter(fileStream))
        {
            streamWriter.Write("this is clear file");
            fileStream.Flush();
            streamWriter.Close();
        }
        fileStream.Close();
    }
    
    //调用Stream的SetLength这个方法,将长度设为0,可以实现清空原有文件
    using (FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Write, FileShare.Write))
    {
        fileStream.SetLength(0);
        using (StreamWriter streamWriter = new StreamWriter(fileStream))
        {
            streamWriter.Write("this is clear file");
            fileStream.Flush();
            streamWriter.Close();
        }
        fileStream.Close();
    }
    
    //如果文件已存在则清空,从Truncate打开的文件中读取将引发异常
    using (FileStream fileStream = new FileStream(file, FileMode.Truncate, FileAccess.Write, FileShare.Write))
    {
        using (StreamWriter streamWriter = new StreamWriter(fileStream))
        {
            streamWriter.Write("this is");
            fileStream.Flush();
            streamWriter.Close();
        }
        fileStream.Close();
    }
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  • 原文地址:https://www.cnblogs.com/lcawen/p/13603022.html
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