C# 新建文本文件

先引入System.IO的命名空间，然后写如下代码
string file = txtFilePath.Text;
string content = txtContent.Text;
if (!File.Exists(file) == true)
{
MessageBox.Show("存在此文件!");
}
else
{
FileStream myFs = new FileStream(file, FileMode.Create);
StreamWriter mySw = new StreamWriter(myFs);
mySw.Write(content);
mySw.Close();
myFs.Close();
MessageBox.Show("写入成功");

}

C#创建txt文件

一、 判断文件是否存在，不存在则创建，存在就往里面写入信息。         if (!File.Exists("F:\\TestTxt.txt"))
            {
                FileStream fs1 = new FileStream("F:\\TestTxt.txt", FileMode.Create, FileAccess.Write);//创建写入文件 
                StreamWriter sw = new StreamWriter(fs1);
                sw.WriteLine(this.textBox3.Text.Trim() + "+" + this.textBox4.Text);//开始写入值
                sw.Close();
                fs1.Close();
            }
            else
            {
                FileStream fs = new FileStream("F:\\TestTxt.txt", FileMode.Open, FileAccess.Write);
                StreamWriter sr = new StreamWriter(fs);
                sr.WriteLine(this.textBox3.Text.Trim() + "+" + this.textBox4.Text);//开始写入值
                sr.Close();
                fs.Close();
            }二、创建txt，并往里面填写信息。       public void CreateFile()
        {
            FolderBrowserDialog folder = new FolderBrowserDialog();
            folder.ShowDialog();
            string path = folder.SelectedPath;
            string name = "\\" + "aa.txt";
            if (!File.Exists(path + name))
            {
                FileStream fs1 = new FileStream(path + name, FileMode.Create, FileAccess.Write);
                StreamWriter sw = new StreamWriter(fs1);
                sw.WriteLine("sfsdfdf");//要写入的信息。 
                sw.Close();
                fs1.Close();
                MessageBox.Show("保存成功！");
            }
        }