使用batch file来插入string

如所承诺的，这是一个Python解决方案。 这个程序在Python 3.x或者Python 2.7中都可以正常工作。 如果你对编程非常陌生，我建议使用Python 3.x，因为我认为它更容易学习。 你可以从这里免费得到Python： http : //python.org/download/

Python的最新版本是3.2.3版本; 我建议你明白

将Python代码保存在名为add_null.py的文件中，并使用以下命令运行它：

 python add_null.py input_file.txt output_file.txt 

代码，有很多评论：

 # import brings in "modules" which contain extra code we can use. # The "sys" module has useful system stuff, including the way we can get # command-line arguments. import sys # sys.argv is an array of command-line arguments. We expect 3 arguments: # the name of this program (which we don't care about), the input file # name, and the output file name. if len(sys.argv) != 3: # If we didn't get the right number of arguments, print a message and exit. print("Usage: python add_null.py <input_file> <output_file>") sys.exit(1) # Unpack the arguments into variables. Use '_' for any argument we don't # care about. _, input_file, output_file = sys.argv # Define a function we will use later. It takes two arguments, a string # and a width. def s_padded(s, width): if len(s) >= width: # if it is already wide enough, return it unchanged return s # Not wide enough! Figure out how many spaces we need to pad it. len_padding = width - len(s) # Return string with spaces appended. Use the Python "string repetition" # feature to repeat a single space, len_padding times. return s + ' ' * len_padding # These are the column numbers we will use for splitting, plus a width. # Numbers put together like this, in parentheses and separated by commas, # are called "tuples" in Python. These tuples are: (low, high, width) # The low and high numbers will be used for ranges, where we do use the # low number but we stop just before the high number. So the first pair # will get column 0 through column 11, but will not actually get column 12. # We use 999 to mean "the end of the line"; if the line is too short, it will # not be an error. In Python "slicing", if the full slice can't be done, you # just get however much can be done. # # If you want to cut off the end of lines that are too long, change 999 to # the maximum length you want the line ever to have. Longer than # that will be chopped short by the "slicing". # # So, this tells the program where the start and end of each column is, and # the expected width of the column. For the last column, the width is 0, # so if the last column is a bit short no padding will be added. If you want # to make sure that the lines are all exactly the same length, change the # 0 to the width you want for the last column. columns = [ (0, 12, 12), (12, 29, 17), (29, 999, 0) ] num_columns = len(columns) # Open input and output files in text mode. # Use a "with" statement, which will close the files when we are done. with open(input_file, "rt") as in_f, open(output_file, "wt") as out_f: # read the first line that has the field headings line = in_f.readline() # write that line to the output, unchanged out_f.write(line) # now handle each input line from input file, one at a time for line in in_f: # strip off only the line ending line = line.rstrip('\n') # start with an empty output line string, and append to it output_line = '' # handle each column in turn for i in range(num_columns): # unpack the tuple into convenient variables low, high, width = columns[i] # use "slicing" to get the columns we want field = line[low:high] # Strip removes spaces and tabs; check to see if anything is left. if not field.strip(): # Nothing was left after spaces removed, so put "NULL". field = "NULL" # Append field to output_line. field is either the original # field, unchanged, or else it is a "NULL". Either way, # append it. Make sure it is the right width. output_line += s_padded(field, width) # Add a line ending to the output line. output_line += "\n" # Write the output line to the output file. out_f.write(output_line) 

运行这个程序的输出：

 field1 field2 field3 AAAAA BBBBB CCCCC DDDDD NULL EEEEE FFFFF NULL NULL GGGGG HHHHH NULL 

我不认为你想在微软“批处理”脚本中做什么。 但是这里有一整套字符串操作符：

http://www.dostips.com/DtTipsStringManipulation.php

但批处理文件是可怕的，我希望你可以使用更好的东西。 如果你想要一个Python解决方案，或AWK，我可以帮你。

如果我是你，而且我确实要用“批处理”脚本来做到这一点，那么我将使用~x,y列切片（其中x是第一列， y是第二列）将每行分成三个子字符串， 。 然后检查每一个是否只是空格，而那些只是空格的替换为“NULL”。 然后重新加入到一个字符串的子字符串，并打印。 做一个循环内，你有你的程序。