C / C++ / MFC

5-Dec-05 23:43

Hi,
I am trying to read data from a textfile, but I can't seem to open the file. Here's the code I use:

<code>void fileOperator::openInputFile(const wchar_t *fname)
{
	inFile.open(fname, std::ios_base::in);
	if(!inFile.is_open() ) 
	{ 
		printf("File could not be opened\n");
		exit(1);
	}
}</code>

I get no error messages from the compiler, but when I run the program, I get the "File could not be opened" error. I have checked that the program and the textfile are in the same directory. This should be the simplest thing and I'm practically tearing my own hair out trying to figure it out. Please help!

Roger

toxcct5-Dec-05 23:56

toxcct

5-Dec-05 23:56

is the function called with a valid file path as a parameter ??
what happens if changing fname from const wchar_t* to const char* ?
where is defined inFile ? is it well initialized ?

TOXCCT >>> GEII power
[toxcct][VisualCalc 2.20]

grero6-Dec-05 0:12

6-Dec-05 0:12

Hi,
Sorry, here is the definition for the class I'm using:

#include <stdio.h>
#include <fstream>
#include <vector>
#include <ios>

class fileOperator {
protected:
	<
	std::ifstream inFile;
	std::ofstream outFile;

public:
	fileOperator() {};
	void openInputFile(const wchar_t *fname);
	void openOutputFile(const wchar_t *fname) {};
	void readMatrix(int numberOfColumns, double **matrix);
};

Using const char* was my first thought too, but my compiler doesn't seem to like it. It claims ifstream::open only accepts wchar_t* as its argument. Here's the compiler error I get:

.\fileTest.cpp(8) : error C2664: 'fileOperator::openInputFile' : cannot convert parameter 1 from 'char *' to 'const wchar_t *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

There might be some blindingly obvious thing I'm missing here as I'm fairly new to C++ Smile | :)

Roger

toxcct6-Dec-05 1:10

toxcct

6-Dec-05 1:10

you have to either wass it a char* string and to change the function prototype !!!

TOXCCT >>> GEII power
[toxcct][VisualCalc 2.20]

grero6-Dec-05 1:29

6-Dec-05 1:29

Sorry about that, with the function prototype changed to char*, the code compiles of course, but I still can't open the file...

Roger

kakan6-Dec-05 0:02

kakan

6-Dec-05 0:02

"wchar_t *fname"?
You might considder "char * fname"?

Or a UNICODE build?

S. Senthil Kumar6-Dec-05 4:10

S. Senthil Kumar

6-Dec-05 4:10

Does the path to the file look like this ?

const char *path = "C:\Test\TestFile.txt";

If that's true, then you need to escape the \ character by addding another \. Like

const char *path = "C:\\Test\\TestFile.txt";

Regards
Senthil
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grero6-Dec-05 8:28

6-Dec-05 8:28

Hi,
Sorry, I'm not using the full path. The file I'm trying to read is in the same directory as the program itself. I tried using full path with the double \\, but to no use. The file still won't open.

Roger

mmx vs. floating point

9ine5-Dec-05 23:38

9ine

5-Dec-05 23:38

I need to get my floating points calculation to run faster, the floating point numbers stored in instances of some class in vector<class> array I just need to multiply them and add result:

class{
float val1;
float val2;
};

for(i=0; i<size; i++)
="" res="" +="class[i]-">val1 * class[i]->val2;

will it be faster to store floating numbers from vector massive to plain floating array

float *ar1, *ar2;
for(i=0; i<size; i++)
="" ar1[i]="class[i]-">val1;
ar2[i] = class[i]->val2;

and then perform mmx calculations or memory moving ops will take also some time so there will be no significant speed increase? Or will it be faster to use compound intrinsics to load floating numbers to float[4] and then perform multiplication?

If some one encountered similar problem?

9ine

C^hris L^osinger6-Dec-05 2:11

C^hris L^osinger

6-Dec-05 2:11

9ine wrote:
perform mmx calculations

MMX instructions are all integer-based, so they can't help you at all with floating point calcs.

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9ine6-Dec-05 3:02

9ine

6-Dec-05 3:02

I know about mmx, by this word I mean all multemedia extensions, it is SSE with floating points which I wonder about for my application if you need me to be more exact.
I can do it my self easely but dont want to waste time if some one done it before an got speed improvement, which I mean:

timemmx = [mem move from classes in vector<> array] + [SSE ops]
timefloat = [standart floating multiplications]

timemmx << timefloat! ??

Otherwise I will need to make much bigger changes in my code to get floating values from my vector<class> to align them in memory, which I'm reluctant.

9ine

C^hris L^osinger6-Dec-05 4:03

C^hris L^osinger

6-Dec-05 4:03

i'm not sure anyone could say for sure without actually trying.

but, items in a vector are stored contiguously in memory, so you can treat them as a plain C++ array. (this is part of the 2003 C++ standard, IIRC - and all implementations store data that way regardless). so, you should be able to load the SSE registers directly from the contents of your vector.

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