Two dimension arrays

[yoitsmejy]

Hi guys, I am trying to figure out how to set up two dimension arrays. I might not be using the right terms but i have 7 columns and a few hundred rows. What I am trying to do is compare the columns and two rows at a time. So comparing row 1 column 1 with row 2 column 1, then would cout if it doesnt fit into the argument. Then move to compare row 2 column 1 with row 3 column 1 and so on... How can I do so? Below is the example of data i will be using. Thanks.


19970929,162.5800,170.3200,157.4200,169.8100,31427893,125.0600
19970930,171.8700,172.9000,170.8400,172.9000,901641,127.3400
19971001,172.9000,177.5500,172.3900,177.0300,1101598,130.3900

[LB]

yoitsmejy wrote:

then would cout if it doesnt fit into the argument.

Could you explain what this means? What do you mean by "fit into the argument"?

[yoitsmejy]

Sorry. If the argument is false.

[LB]

Ah. Well, you can loop through each column, and in that loop loop for #rows-1 times, then just compare current row,col to row+1,col

[yoitsmejy]

LB, I've been trying to figure it out but was not able to get it to work.

ifstream indata("Test.csv");
	

	while (!indata.eof())		// keep reading until end-of-file
	{  
  
		float colA,  colB,  colC,  colD,  colE,  colF,  colG;	
		float pcolA, pcolB;
		
		pcolA=colA+1;

		//Get data
		indata >> colA >> colB >> colC >> colD >> colE >> colF >> colG;

		ofstream gaps("Rec.txt");
		//Do your comparisons
		if( abs(colA - pcolA) > 5 && pcolA > 0)
			gaps << "Gap in days" << colA << endl;
		gaps.close();
		//Set your references for next time

	}
	indata.close();

[Cubbi]

The programming problems are:
1) while (!indata.eof())
2) pcolA is recreated for every line and given an indeterminate value
3) indata >> colA >> colB >> colC >> colD >> colE >> colF >> colG; requires whitespace separators by default, but you have comma separators

fixing those gives

    ifstream indata("Test.csv");
    unsigned long pcolA = 0;
    string line;
    while (getline(indata, line))
    {
        unsigned long colA;
        istringstream(line) >> colA;
        ofstream gaps("Rec.txt");
        if( abs(colA - pcolA) > 5 && pcolA > 0)
            gaps << "Gap in days at " << colA << '\n';
        pcolA = colA;
    }

But there is an error in the algorithm as well: subtracting *dates* in YYYYMMDD format does not exactly give the difference in *days*: 19971001 - 19970930 == 71, not 1. Consider parsing dates as actual dates, using a suitable library (try boost if you can, or if your compiler is sufficiently modern to have C++11's std::get_time in <iomanip>, use that)

[yoitsmejy]

the code works great. I tried adding another if argument and when it runs, rec.txt file is empty.

Below is the code that i added,

int main () 
{
  ifstream indata("Test.txt");
    unsigned long pcolA = 0;
	unsigned long pcolB = 0;
	unsigned long pcolC = 0;
	unsigned long pcolD = 0;
	unsigned long pcolE = 0;
	unsigned long pcolF = 0;
	unsigned long pcolG = 0;

    string line;

    while (getline(indata, line))
    {
		unsigned long colA;
		unsigned long colB;
		unsigned long colC;
		unsigned long colD;
		unsigned long colE;
		unsigned long colF;
		unsigned long colG;
		istringstream(line) >> colA >> colB >> colC >> colD >> colE >> colF >> colG;

        ofstream rec("Rec.txt");
		string gaps;
		string change;
        if((colA - pcolA) > 5 && pcolA > 0)
            cout << gaps << "Gap in days at " << colA << endl;
		if(colB > (1.1 * pcolB) > 0)
			cout << change << "More than 10% change at" << colA << endl;

		cout << rec << gaps << '\n' << change << endl;

        pcolA = colA;
		pcolB = colB;
		pcolC = colC;
		pcolD = colD;
		pcolE = colE;
		pcolF = colF;
		pcolG = colG;
		}
	indata.close();
  return 0;
}

How can i fix the error?