How do I merge two files with two columns side by side in one file?

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hi;

how can i copy two files in one file, supposed that each file contain one column of data, into one file without reading variables and put them in another file, ordinary procedure is two read content of each file and put them into another one, which consume much time when dealing with large data, i mean merge two columns side by side in one file, any creative ideas.

Example Inputs : file 1

Example Inputs : file 2

Desired Output : "resulted file"

thanks

What I have tried:

C++

FILE *fptr,*fptr1,*fptr2;
char string1[2000],string2[2000];


fn1.Format("d:\\file_1.txt");
fn2.Format("d:\\file_2.txt");
fn.Format("C:\\file_3.txt");

fopen_s(&fptr,fn1,"rb");
fopen_s(&fptr1,fn2,"rb");
fopen_s(&fptr2,fn,"wb");

while(fgets(string1,sizeof(string1),fptr)!=NULL)
{
    fgets(string2,sizeof(string2),fptr1); 
    fputs (string1,fptr2);
    fputs (s"\t",fptr2);
    fputs (string2,fptr2);
}

fclose(fptr);	
fclose(fptr1);
fclose(fptr2);

note: the two files are the same in length

Posted 29-May-16 11:21am

aymanshebl

Updated 29-May-16 19:17pm

PIEBALDconsult

v3

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Comments

Maciej Los 29-May-16 17:25pm

And what have you tried?

aymanshebl 29-May-16 17:28pm

well, i tried to scanf variables from file one and file two and put data into another file, but i want effective , more speedy way than i do

Sergey Alexandrovich Kryukov 29-May-16 17:40pm

Who are you talking to? To reply to the question by Maciej Los, you have to reply on his comment, not on your own post, then he will get a notification on your comment.

Apparently, you did not understand the question "What have you tried?" This is more detailed formulation of this question:
What have you tried so far?

What makes you thinking that your approach was too slow? With such small files, you hardly can notice the time spend on this operation.

—SA

aymanshebl 29-May-16 17:47pm

take it easy man,

honestly, i reply to him not my post

i give small example, what i am doing is more than 50000 reading in each file

your help will be appreciated

thanks

Sergey Alexandrovich Kryukov 29-May-16 17:54pm

You manner to ignore comments and make your comments not noticed by people who you are talking to won't get you anywhere. Why not paying a bit of attention — this is really simple?
I repeat: technically, you replied to your own post.

I guess, you will probably get some help when you write what you have tried. Chances are, you already did it all correctly. However, the whole idea of using all those files could be replaced with something more reasonable, but as soon as you really need to do what you do, you hardly can improve it much.

—SA

aymanshebl 29-May-16 18:10pm

my apologies from you, sorry for this misunderstanding

this is my code

FILE *fptr,*fptr1,*fptr2;
char string1[2000],string2[2000];

fn1.Format("d:\\file_1.txt");
fn2.Format("d:\\file_2.txt");
fn.Format("C:\\file_3.txt");

fopen_s(&fptr,fn1,"rb");
fopen_s(&fptr1,fn2,"rb");
fopen_s(&fptr2,fn,"wb");

while(fgets(string1,sizeof(string1),fptr)!=NULL)
{
fgets(string2,sizeof(string2),fptr1);
fputs (string1,fptr2);
fputs (s"\t",fptr2);
fputs (string2,fptr2);

}

fclose(fptr);
fclose(fptr1);
fclose(fptr2);

note: the two files are the same in length

Patrice T 29-May-16 18:39pm

Use Improve question to update your question.

PIEBALDconsult 29-May-16 20:51pm

I doubt you want to read and write in binary mode.
And I think fputs (s"\t",fptr2); is wrong

aymanshebl 30-May-16 14:40pm

it is typing mistake

the correct code will be

fputs ("\t",fptr2);

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Garth J Lancaster · Answer 1 · 2016-05-29T13:32:00

you've tagged your solution 'c++', 'c', 'MFC' - yet your code is clearly 'c'

There are a couple of worries with this sort of question - you say more than '50000' in each file - are we to assume they are all 'single' character lines like your examples (in which case why have you defined 2000 long char arrays ?)

It could take a while/experimentation to 'make it faster' - and what do you define as 'fast' or 'slow' ? (you must realise a lot of I/O is happening)

# one approach (that I would use) may be to use c++, std::ifstream and std::list, read the files into memory and then output them using iterators and std::ofstream - the intent being that ifstream and ofstream provide some buffering as to reduce the locks in i/o from disk

# as a 'step back' from the approach above, I wonder if ifstream/ofstream are faster than fgets/fputs ... you could simple upgrade your code in 'c' to 'c++' and try it

There's no point in quoting 'faster' / 'slower' unless you're measuring times though, so you need to get start and end times for your processes/attempts and compare them