怎么批量修改txt文件中的数字？新手多指教啊
列如：1,,506211.740,3440499.504,415.475
2,,506198.111,3440507.274,417.892
3,,506226.324,3440510.430,418.978
4,,506322.723,3440477.461,419.517
5,,506321.051,3440457.492,418.000
改成
1,,506211.740,3440499.504,416.475
2,,506198.111,3440507.274,418.892
3,,506226.324,3440510.430,419.978
4,,506322.723,3440477.461,420.517
5,,506321.051,3440457.492,419.000
