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Hi,
i would like to read data from a tab delimited txt file:in this file there are 7 columns,each representing a physical quantity.
After this reading operation i want to fill some arrays in order to plot the various quantities.
Can you give me some advice?
Thanks in advance!
You can read the file line by line and then tokenize the line on a tab-character to split it.
if your file is tab delimited all the way, then you can read it like that:
just make sure how the data types are stored...in my code i assume that all file is contains int values! if you have different data types you should change the fscanf.Code:FILE *fp = ::fopen( "c:\\file.txt" ,"r");
if (!fp)
return;
while ( fp && feof(fp) == 0 )
{
int a=0,b=0,c=0,d=0,e=0,f=0,g=0;
::fscanf(fp,"%d\t%d\t%d\t%d\t%d\t%d\t%d\n",&a,&b,&c,&d,&e,&f,&g);
}
::fclose(fp);
Cheers
I'd go for Marc's solution as it is more flexible. and, to make lifemuch easier I would take boost lib and use the tokenizer class there.
How can i read the file line by line?Quote:
Originally Posted by Marc G
What do you mean with "tokenize"?
1) If there are always 7 fields, you can read as follows (fields
are separated by any whitespaces). Sample below has fields
of different types:
Code:#include <fstream>
int main()
{
int i1,i2,i3,i4;
float f1,f2;
double d1;
std::ifstream in("your_file.txt");
while (in >> i1 >> i2 >> f1 >> d1 >> i3 >> i4 >> f2)
{
// do whatever you want
}
return 0;
}
2) if number of fields is unknown, but all of the same type, you can read
as follows (again, separated by any whitespaces):
Code:#include <fstream>
#include <sstream>
#include <vector>
int main()
{
std::ifstream in("your_file.txt");
std::string line;
while (std::getline(in,line))
{
std::vector<int> v;
std::stringstream ss(line);
int ival;
while (in >> ival)
v.push_back(ival);
// do whatever you want with v[0] ... v[v.size()-1]
}
return 0;
}
Use std::getline, see the second example by Philip Nicoletti above.Quote:
Originally Posted by Fraben
Tokenize means to split a string up by splitting it on a certain character, in your case a tab-character. In your case you can easily tokenize it like Philip Nicoletti said by using the >> operator. Note: this will split your string on any white-space, not just a tab-character.Quote:
Originally Posted by Fraben
Thanks for your precious help!
2 more questions:
1)The text file i'm reading contains three initial lines:an empty line,an header (which explains which data is represented below),and a "delimiter" realized with some "-" (i.e. somewhat like ----------------).
How can i exclude these lines?They force the while to stop immediately!
2)In the code you've sent to me i've seen you have used std::ifstream.Can i use CFile instead?
If it are exactly 3 lines, you can call std::getline 3 times to skip those lines.Quote:
Originally Posted by Fraben
Thanks Marc,it works perfectly!
But what can i do to check the line before reading it?
I mean:suppose that there's a line with only one string of text,which i want to ignore,and i don't know where it is.
Is there a way to exclude it,in order to let the "while" instruction work correctly,reading till the end of the file?
well you dont need to check line before reading it. you should read the line check if you want to ignore the data if yes continue else process the data.Quote:
Originally Posted by Fraben
look at this pesudo code:
CheersCode:while ( !END_OF_FILE)
{
ReadLine( Line );
// check the Line data
if ( dont want Line )
continue;
// here process the Line and do whatever you want
}
golanshahar: i agree with you,but how can i do what you've suggested?
I don't know much about file handling(well,i don't know much about visual c++...,i'm a rookie!),and i'm trying to use the code sent by Philip Nicoletti.
well if you using Philip code then its simple:Quote:
Originally Posted by Fraben
Philip i hope its ok i used your code ;)Code:std::ifstream in("your_file.txt");
std::string line;
while (std::getline(in,line))
{
// here you have line
// check the line if it something that you want or not i dont know
// what is your cases to "Want" a line or not.
if ( line == "something i dont want")
continue;
std::vector<int> v;
std::stringstream ss(line);
int ival;
while (in >> ival)
v.push_back(ival);
// do whatever you want with v[0] ... v[v.size()-1]
}
hope its help...
Cheers
Hi,
i've used this code
But during the debugging, i've noticed that the data variable,which i know is "11/03/06" in the file i open,is read as:Code:void CApiarioDlg::OnLoadData()
{
char data[8],ora[8];
double TempMis,TempSet,Umid,Press,Weight;
CString strHour,strMinute,strDate,strForTitle;
long lHour,lMinute;
if(!g_pLoadGraph)
g_pLoadGraph=new CLoadGraph(this);
char strFilter[]={"TXT Files (*.txt)|*.txt|All Files (*.*)|*.*||"};
CFileDialog fdlgChoose(TRUE,".txt",NULL,OFN_READONLY,strFilter);
// CFileDialog filedlgFileChoose(TRUE,".wav");
if(fdlgChoose.DoModal()==IDOK)
{
std::ifstream in(fdlgChoose.GetPathName());
std::string line;
for(int i=1;i<=5;i++)
std::getline(in,line);
while(in>>data>>ora>>TempMis>>TempSet>>Umid
>>Press>>Weight)
{
g_pLoadGraph->m_LoadMultiGraph.SetLoadingData(TRUE);
strHour=ora;
strHour=strHour.Left(2);
lHour=atol(strHour);
strMinute=ora;
strMinute=strMinute.Mid(3,2);
lMinute=atol(strMinute);
g_pLoadGraph->m_LoadMultiGraph.InsertData5(TempMis,TempSet,Umid,Press,Weight,
lHour,lMinute);
g_pLoadGraph->m_LoadMultiGraph.DrawNow();
}
strDate=data;
}
}
As you can see,the first character read is a null character.Why?How can i fix it?Code:- data 0x00120f6c ""
[0] 0 ''
[1] 49 '1'
[2] 47 '/'
[3] 48 '0'
[4] 51 '3'
[5] 47 '/'
[6] 48 '0'
[7] 54 '6'
change ur for loop like this
Code:for(int i=0;i<=5;i++)
{
}
I've tried to apply your change Gunaamirthavelu,but unfortunately it doesn't work...
It seems that when i do:
,where data and ora are char[8] and the others double,the first character read,i.e. the one stored in data[0],is an empty character..Code:while(in>>data>>ora>>temperatura>>umidita>>pressione>>peso>>velvento>>pioggia>>radsol)
I don't really have a clue about this,can you help me?
The simplest way for us to help you would be by seing the program and the test data. Upload the text file as well as the project (actually a trimmed down version that replicates the problem would be better).
Here's a small test application with one of my archives.
when posting code you should delete all the obj, ncb, pch files from the archive.
Sorry...
Yuor problem is cause by a write outside bounds. You define date and ora as
char date[18],ora[18]; and you read from file values such as 22/03/06 and 16:44:26.
The problem is that in >> data and in >> ora will write 9 chars in your variables not 8. The 9th ( warrior) is the terminating 0.
Note: due to how your variables are layed out in memory, the 9th char in ora happens to be the 1st in data, thus in >> ora, by writting 9 chars, will "empty" data ( its first char is 0).
You could try to solve this issue by increasing the size of your char arrays but this kind of problem can comeback at any change of the file layout. The safest option is to use std::string instead.
Code:std::string date, ora;
double temperatura,umidita,pressione,peso,velvento,pioggia,radsol;
CString strHour,strDate;
char strFilter[]={"TXT Files (*.txt)|*.txt|All Files (*.*)|*.*||"};
CFileDialog fdlgChoose(TRUE,".txt",NULL,OFN_READONLY,strFilter,this);
if(fdlgChoose.DoModal()==IDOK)
{
std::ifstream in(fdlgChoose.GetPathName());
std::string line;
std::getline(in,line);
std::getline(in,line);
std::getline(in,line);
std::getline(in,line);
std::getline(in,line);
std::getline(in,line);
std::getline(in,line);
while(in>>date>>ora>>temperatura>>umidita>>pressione
>>peso>>velvento>>pioggia>>radsol)
{
//strHour=ora;
//strDate=date;
}
}
Thank you so much!