Once again no data from file

[electro amperkin]

So I rewrited my code and suddenly same problem occured.

source code : https://drive.google.com/open?id=1GdOu5BbH8bbJFbkn_1NYUVZyt_Ty8WA-


About problem : I extracted data from file it was ok, but when multiplied all the coefficients the result was wrong, even on the low numbers.

  // Abbriviated Multiplication Formula calculator using Pascal's triangle concept

#include <iostream>
#include <cmath>		
#include <fstream>	
#include <sstream>

using namespace std;

int main (void) {
	
	const int MAX_ARRAY_SIZE = 16;
	
	long int pascalData[MAX_ARRAY_SIZE];		// or coefficients
	unsigned long long int firstVar[MAX_ARRAY_SIZE]={1}, secondVar[MAX_ARRAY_SIZE]={1}, result[MAX_ARRAY_SIZE]={1};
	
	int kA, kB, powerNum;
	
	cout << "Welcome to the AMF Pascal coefficients calculator! \n";
	
	cout << "Enter coefficients of the formula \" (Ax +- By)^N \" A, B, N: ";
	cin >> kA >> kB >> powerNum;
	cout << endl;
	powerNum ++;						// just for convinience in lines 42, 47 
	
	// first read coefficients from table/triangle and write it to array...
	
	ifstream readTable ("pascal.txt");
	
	string bufferString;
	
	for (int i=0; i<powerNum; i++) {		// getting to the right line
		getline (readTable, bufferString);
	}
	
	stringstream bufferSS;
	bufferSS << bufferString;
	
	for (int i=0; i<powerNum; i++) {	// this loop will extract integers from bufferString
		bufferSS >> pascalData[i];
	}
	
	for (int i=0; i<powerNum; i++) {	
		firstVar[i] = pow(kA, powerNum-i);
		secondVar[i] = pow (kB, i);
	}
	
	for (int i=0; i< powerNum; i++) {		// multiplying data to get the resulting coefficients
		result[i] = firstVar[i] * secondVar[i] * pascalData[i];
	}
	
	for (int i=0; i<powerNum; i++) {			// output
		cout << result[i] << endl;
	}
}

[helios]

I see that you're using integers everywhere, but also using pow().
1. What sort of exponents and bases are you handling?
2. pow() is a floating point function. Are you expecting exact results even in the unit digit, or are you content with approximate results?

You may need to use a bignum library to get the results you're expecting.

[electro amperkin]

Hi helios,

I am not going to use floating point data so int's are ok but as you mentioned I need bignum library. I will search for one but it would be great if you give an example code.

[Handy Andy]

Hello electro amperkin,

I have to ask on line 28 you define the file stream and open the file, but how do you know that it opened?

What you want is something like this:

ifstream readTable("pascal.txt");

if (!readTable)
{
	std::cout << "\n    File \"pascal.txt\" did not open!\n";

	return 1;
}

Otherwise your program would continue even if the file did not open.

It would also help if you would include the input or a good sample to work with so everyone can use the same information.

Andy