Printable View
Hi everyone,
I have just start working at my final year project in communication engineering and I’m doing some c++ programming as well. My question is how can I read numbers from a .txt or .xls file and make some calculation with it, then output this calculation in another .xls file.
Lets say the file that I want to read from contains: "4 5"
and i would like to create another .xls file that contains: "4 5 9" (9 is the sum of the two numbers)
please everyone I need your help ASAP
cheers
http://wotsit.org/
Or search for XLS reading libraries. Note that Microsoft changes their formats very often, so supporting them all is extremely difficult.
You'd be much better off simply supporting comma-separated value files, CSVs. Excel can import and export them, as can every other program working with tables.
As for text I/O, that should be simple enough.
Stick to text files, it will make your life SO much easier.
"As for text I/O, that should be simple enough."
"Stick to text files, it will make your life SO much easier."
thanks for your help CornedBee and Salem, i think i will do my work in txt files to avoid any problems, BUT i still didn't know what to write?? what is the source code??:confused:
Do you know how to read text files in general?
For CSV files, you read the text file line by line and split each line into the fields. You can use the Boost.Tokenizer library there.
Ok, so show us where you are stuck? Generally, we don't write code for beginners - it's much better that you do it yourself, and when you don't know what to do, ask here [with a SMALL example of your code - not hundreds of lines]. It also helps if you are precise about what you are experiencing difficulty with - e.g. if you are trying to add two numbers together, what numbers are you using, and what result do you get [and if it's not absolutely obvious, what do you EXPECT it to be].
There are plenty of tutorials on "reading data from a file" on this site and in other places.
Go to www.cprogramming.com for tutorials.
Doing math on the data depends a little bit on what you actually want to do, and what sort of data you have, and so on.
Do you have a book on C++ - if not, there's a "book recommendations" thread that you should be able to find a few suggestions in.
--
Mats
ok to save everyone's time this is what i wrote earlier:
********************************************
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
char str[20];
fstream file_op("test.txt"); // "test.txt" contains two numbers 3 and 5 separated by space
while(file_op >> str)
cout << str ;
file_op.close();
return 0;
}
***************************************
so from this source code it will read the two numbers from the txt file and output them ....
BUT instead of that i would like to output the two numbers in another txt file and inside it i want this to be shown:
a=3 b=5 c=8
thats all .....??
Please use [code][/code] tags to post code. It preserves the formatting.
Inside what do you want what to be shown? Where do a, b and especially c come from?
first, i would thank you CornedBee for your question and your patient with me. second, i really can't explain more about what i want so if you tell me what you have understand from what i wrote and i'll make some edit on what you'll say.Quote:
Originally Posted by CornedBee
cheers
Well, the first thing is, do you know how to write to another text file as well?
BTW, you probably want to read data into an integer, not a string.
So, you have a file like
and you want to generate another file likeCode:3 5 8
Is that right?Code:a=3 b=5 c=8
>> second, i really can't explain more about what i want so if you tell me what you have understand from what i wrote and i'll make some edit on what you'll say.
do you really expect to be spoon fed the answer? a little more effort, please.
You want to do two things:
1) "i would like to output the two numbers in another txt file"
2) "inside it i want this to be shown:
a=3 b=5 c=8"
Where do these three numbers come from, and why are they called a, b and c? Do you want the output from #2 to be inside the text file as well?
yes, i now how to write to another text file.Quote:
Originally Posted by dwks
yes, i have a txt file like: 3 5
no, i want to generate another txt file like: a=3 b=5 c=8 \\ where c=a+b=8
i want to do three things:Quote:
Originally Posted by CornedBee
1) read in integers from a txt file \\ which are: 3 5
2) import this integers and defined 3 as "a" and 5 as "b" then add 3 and 5 together to present c
3)then generate #2 to another txt file.
thats all...
care to post the code you have thus far?
this is the code:Quote:
Originally Posted by Sebastiani
**************************************Code:#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main ()
{
string line;
ifstream data;
data.open ("input.txt");
while (!data.eof())
{
getline(data, line);
}
ofstream result;
result.open ("output.txt");
result << line;
result.close ();
data.close ();
return 0;
}
in this code i import and export "line" from the files which is not what i'm looking for, i want to import and export individual integers from the files
What did I tell you about code tags?
i'm so so sorry i made an editQuote:
Originally Posted by CornedBee
Bad idea. http://faq.cprogramming.com/cgi-bin/...&id=1043284351Code:while (!data.eof())
Well, here's what your code does right now.Quote:
in this code i import and export "line" from the files which is not what i'm looking for, i want to import and export individual integers from the files
- Read lines until the end of the input file.
- Write the last line read to the output file.
In effect, it writes the last line of the input file to the output file.
What you need to do is to read integers, not lines. Since you know the format of the input file, you could probably
- read the integer a from the input file;
- read the integer b from the input file;
- calculate the sum of these two numbers, storing the result in c;
- write a, b, and c to the output file.
Does that give you any ideas?
in.txtCode:// Assuming only 26 numbers on 1 line
#include <fstream>
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main(void)
{
ifstream input("in.txt");
ofstream output("out.txt");
string line;
stringstream ss;
double num;
double sum;
char idx;
while ( getline(input, line) )
{
ss << line;
sum = 0;
idx = 'a';
while (ss >> num)
{
output << idx++ << '=' << num << ends;
sum += num;
}
output << idx << '=' << sum << endl;
ss.clear();
}
input.close();
output.close();
return 0;
}
out.txtCode:3 5 7 6 9
4 5 6 3 2 1 3 43 66 34 12 76 34
1 2 3
Code:a=3 b=5 c=7 d=6 e=9 f=30
a=4 b=5 c=6 d=3 e=2 f=1 g=3 h=43 i=66 j=34 k=12 l=76 m=34 n=289
a=1 b=2 c=3 d=6
Yes, well, that's one way to do it. However, your variable names are pretty terse -- it's generally best to use longer names when you're posting code for others to learn from. And really, that's not the easiest code for someone to learn from; it's too complicated. You have to figure that someone who can't read two numbers, add them, and print them isn't going to learn much from something like that.
In addition, if you're going to all of the trouble to use a vector, don't hard-code the size of the vector into the program. That's one nice thing about vectors -- they can expand to hold new data as you see fit.
[edit] On the other hand, you don't need to remember previous numbers at all. See below. [/edit]
Really, it's quite simple. As long as you know there are two numbers:
If you want to sum some arbitrary number of numbers, it's easier to keep a running total. With only one line, something like this would work.Code:int a, b, c;
input >> a >> b;
c = a + b;
output << a << ' ' << b << ' ' << c << '\n';
With multiple lines, it might be necessary to read each line separately and parse that string with stringstreams as knave has shown.Code:int var, sum = 0;
while(input >> var) {
output << var << ' ';
sum += var;
}
output << sum << '\n';
Thank you Knave for your code, its exactly do what I need...:cool:
you're right dwks i didn't understand a lot from the code and there are a lot of new codes that I've to understand before i used it...Quote:
You have to figure that someone who can't read two numbers, add them, and print them isn't going to learn much from something like that.
cheers
Sorry if I sounded insulting, but knave's code really was pretty complicated before [s]he edited it. :)Quote:
you're right dwks i didn't understand a lot from the code and there are a lot of new codes that I've to understand before i used it...
@knave: One last thing: you do know that the std::ends manipulator function prints a NULL, right?
I would think a simple space would be better . . .Code:output << idx++ << '=' << num << ends;
Oh, and how did you syntax highlight that code? ;)