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Jul 21st, 2005

Read comma separated data from a text file

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Hi there,

I am trying to make a piece of code in C that:

1. opens a specified file,
2. Reads the data in the file and separates it into two arrays, based on the position of commas,
3. Converts the strings into doubles and then perfoms some manipulation on them,
4. returns the new values to a second text file.

I can do 1,3 & 4, just can't seem to get point 2 to work. The data I have is in the format:

0.000,1
0.001,2
0.002,4
0.003,1
0.004,5
0.005,3

and I want to end up with two arrays of the form:

a[6] = {0.000,0.001,0.002,0.003,0.004,0.005};
b[6] = {1,2,4,1,5,3};

Any offers?

cheers, Ravenous.

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ravenous

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Jul 21st, 2005

Re: Read comma separated data from a text file

looking at the strings library, you could do the following:

C Syntax (Toggle Plain Text)
char *ptrtocomma;
 
if(ptrtocomma=strchr(Inputstringname, ',')!=NULL)
{
outputarray[i]=*++ptrtocomma;
i++;
}
char *ptrtocomma;

if(ptrtocomma=strchr(Inputstringname, ',')!=NULL)
{
outputarray[i]=*++ptrtocomma;
i++;
}

strchr returns a character pointer to the first occurance of the second argument (a character) in the character array designated by the first argument.

Drowzee

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Jul 21st, 2005

Re: Read comma separated data from a text file

C Syntax (Toggle Plain Text)
while(fgets(line, sizeof line, file)}
{
   if(sscanf(line, "%lf,%d", &a[i], &b[i]) == 2)
   {
      ++i;
   }
}
while(fgets(line, sizeof line, file)}
{
   if(sscanf(line, "%lf,%d", &a[i], &b[i]) == 2)
   {
      ++i;
   }
}

Dave Sinkula

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Jul 21st, 2005

Re: Read comma separated data from a text file

That's much nicer... Wow.

Drowzee

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Apr 12th, 2007

-1

Re: Read comma separated data from a text file

Click to Expand / Collapse Quote originally posted by Dave Sinkula ...

C Syntax (Toggle Plain Text)
while(fgets(line, sizeof line, file)}
{
   if(sscanf(line, "%lf,%d", &a[i], &b[i]) == 2)
   {
      ++i;
   }
}
while(fgets(line, sizeof line, file)} { if(sscanf(line, "%lf,%d", &a[i], &b[i]) == 2) { ++i; } }

Hi, how if each row contains large number of elements in 1 row of a large matrix? For example I have a matrix of 100x100 which already stored in a text file, each line contains 100 elements of 1 row of the matrix, seperated by a tab (\t). How could I read the file back into a matrix structure?

Many thanks,
Fantabk

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Apr 13th, 2007

Re: Read comma separated data from a text file

Show us what you have and we can help you fix it. But do it in an new thread. It's not nice to hijack someone else's thread.

WaltP

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This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

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