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Read comma separated data from a text file

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Join Date: Jul 2005

Posts: 23

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ravenous

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Read comma separated data from a text file

Jul 21st, 2005

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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Join Date: Jul 2005

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Drowzee

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Re: Read comma separated data from a text file

Jul 21st, 2005

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

 Help with Code Tags 
 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.

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Join Date: Apr 2004

Posts: 4,335

Reputation: Dave Sinkula has a brilliant future

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Dave Sinkula Dave Sinkula is offline

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long time no c

Re: Read comma separated data from a text file

Jul 21st, 2005

 Help with Code Tags 
 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;
   }
}

"One of the methods used by statists to destroy capitalism consists in establishing controls that tie a given industry hand and foot, making it unable to solve its problems, then declaring that freedom has failed and stronger controls are necessary." --Ayn Rand

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Join Date: Jul 2005

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Drowzee

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Re: Read comma separated data from a text file

Jul 21st, 2005

That's much nicer... Wow.

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Join Date: Apr 2007

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fantabk

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Re: Read comma separated data from a text file

-1

Apr 12th, 2007

•

Originally Posted by Dave Sinkula

Help with Code Tags

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