[SOLVED] Passing 2D array to a function

[gunman353]

I am trying to pass a 2D double array and a 1D string array to a function.

int main()
{

	const int NUM_COMPANIES = 6;
	const int NUM_QUARTERS = 4;
	void writeData(double[][NUM_COMPANIES], string[], int, int); //function prototype
	string companyNames[NUM_COMPANIES] = { "ABC", "DEF", "GHI", "JKL", "MNO", "###" };
 //declare a one dimensional string array to hold the names of 6 different companies
	double salesData[NUM_QUARTERS][NUM_COMPANIES] =
 //a 2D double array to hold the sales data for the four quarters in a year
	{ { 40000, 50000, 60000, 70000 },
	{ 35000, 45000, 55000, 65000 },
	{ 25000, 26000, 27000, 28000 },
	{ 31000, 32000, 33000, 34000 },
	{ 42000, 43000, 44000, 45000 },
	{ 10000, 20000, 30000, 40000 } };

	writeData(salesData, companyNames, NUM_COMPANIES, NUM_QUARTERS);

	system("pause");
	return 0;

void writeData(double salesData[][NUM_COMPANIES], string companyNames, int NUM_COMPANIES, int NUM_QUARTERS)  //In Main, call a function WriteData
{ 
//...
	}

The issue is that when when I say void writeData(double salesData[][NUM_COMPANIES] it tells me that NUM_COMPANIES is unidentified. Why didn't it get passed to the function from main?

[AbstractionAnon]

That's because NUM_COMPANIES is local scope within main. It can't be seen outside of main. Move line 4 to before line 1.

[Duthomhas]

Typically when dealing with fixed-size arrays it is a good idea to typedef them.

typedef double SalesData[ 4 ][ 7 ];

void writeData( SalesData salesData, ... );

SalesData salesData = 
{
  {...},
  ...
};

Keep in mind that you have ordered the dimensions in an inconvenient way. What if you want to deal with more companies? (There will always be four quarters.)

typedef double QuarterlyData[ 4 ];

void writeData( QuarterlyData companySales[], int num_companies, ... );

const int NUM_COMPANIES = 8;
QuarterlyData sales[ NUM_COMPANIES ] = ...

This of course makes adding companies at runtime easier:

QuarterlyData sales[ 100 ]; // maximum of 100 companies
int num_companies = 0;

// add a company:
sales[ num_companies ][ 0 ] = ...
sales[ num_companies ][ 1 ] = ...
...
companyNames[ num_companies ] = ...
num_companies += 1;

// add a company using a function that sets an argument QuarterlyData
void set_company_sales( QuarterlyData quarterlyData );
set_company_sales( sales[ num_companies++ ] );

Hope this helps.