Sorting file using delimiters

[jan3239]

I was wanting to know how you would sort a file based on this style.

name1
line of info
line of info

name2
line of info
line of info

etc..

I would want it to sort each set of 3 lines by the name in the first line of each. Any help would be appreciated.

[Duthomhas]

Create a struct or class that holds the information from the three lines.
Read the file into a deque of those structures.
Use the sort algorithm (#include <algorithm>) with a custom sort function to sort the deque.
Write the deque of structures back out to the file (overwrite it).
Hope this helps.

[Galik]

You could create a struct to contain your lines of data and then read your file into a std::map using the first line as the key. That will order your structs alphabetically according to the names. Then just write the data out to a new file using a std::map::iterator.

[kfmfe04]

Could be cleaner, but here's a two minute quickie one liner on the command-line:

paste -d"|" - -< input.txt | paste -d"|" - - | sort -t"|" | nawk 'gsub("\\|", "\n")'

This is obviously quick-and-dirty and assumes that there are no pipes in the input file, but it gets the job done without having to pull out the big C++ hammer. If you plan on reuse, then coding it up in C++ may be a better choice.

But if you just want to get the job done, there are a myriad of choices from UNIX one-liners to perl or Ruby or python. All these scripting languages are actually very decent choices for text processing, in most cases.

input.txt

name3
Random Line 3.1
ABCDEFG 3.2
hijklmn 3.3
name9
FirstLineOf 9.1
ZYX 9.2
ABC 9.3
name2
2.1
2.2
2.3

output

name2
2.1
2.2
2.3
name3
Random Line 3.1
ABCDEFG 3.2
hijklmn 3.3
name9
FirstLineOf 9.1
ZYX 9.2
ABC 9.3

[jan3239]

Thanks for all of the help. This was all very useful to me. I was looking for the quick and dirty version but the structs information help as well.