argv

**taurus** · 10-14-2007

hi im trying the following pseudocode:

Code:

Algorithm image
CHARACTER cla

output 'Welcome to my program'
input argv[count]
	
	if argv = -i
		output 'You have decided to invert the image'
		..CALL FUNCTION..
	elseif argv = -h
		output 'You have decided to scroll the image'
		..CALL FUNCTION..
	else 
		output 'ERROR: Incorrect argument'
		return 0
	endif
end algorithm

do i need a for loop for it?
Now for argv does it seem right? like will it perform what iv asked?

**laserlight** · 10-14-2007

do i need a for loop for it?

Why would you need a loop? Also, what is argv? If it refers to the command line arguments, then "input argv[count]" is rather unnecessary.

Now for argv does it seem right? like will it perform what iv asked?

Yes, of course, if you are able to correctly translate the pseudocode into code.

**taurus** · 10-14-2007

ok cool, but what if i was to enter 2 arguments like:
a.out -i 45

wont i need an array for that then or how to i deal with it to use the -i and then be able to use the 45 somewhere as well?

**laserlight** · 10-14-2007

You might want to brush up your knowledge of command line arguments by reading cprogramming.com's tutorial on Accepting command line arguments.

**taurus** · 10-14-2007

so basically each CLA is a position, so a.out is at 0, so -1 is at 1, 45 is at 2? am i correct

**laserlight** · 10-14-2007

Yes, though in your example it is -i, not -1, that is at position 1.

**taurus** · 10-14-2007

oh yea sorry wrong input, thanks

**taurus** · 10-14-2007

i am totally confused on how to get an image into an array, i got the following library:

Code:

// This must be called before you start using the library of routines
void ep100_lib_init();

//  This routine will open the image whose full path is specified as a parameter
//  It will return a 1 on error (probably cannot open file) and a 0 on success
int ep100_lib_open_image(char * filename);

// This function returns the width in pixels of the loaded image.
int ep100_lib_get_image_width();

// This function returns the height in pixels of the loaded image.
int ep100_lib_get_image_height();

// This routine will put the image pixel data into the supplied matrix
// from top left to bottom right. You must ensure that enough space is
// available.
void ep100_lib_get_data(int data[EP100_LIB_MAX_X][EP100_LIB_MAX_Y]);

// This routine will set the image pixel data from the supplied matrix
// from top left to bottom right. You must ensure that enough space is
// available.
void ep100_lib_set_data(int data[EP100_LIB_MAX_X][EP100_LIB_MAX_Y])

Now how do i put the image in an array.
is it:

int array[data[EP100_LIB_MAX_X][EP100_LIB_MAX_Y]]?

OR is it

int array[ep100_lib_get_data(data)]?

**matsp** · 10-14-2007

What kind of data type would you call this:

Code:

int data[EP100_LIB_MAX_X][EP100_LIB_MAX_Y];

--
Mats

**taurus** · 10-14-2007

2-D array?

**matsp** · 10-14-2007

correct. So how do you think you should use a function that takes this 2D array as a parameterl?

--
Mats

**taurus** · 10-14-2007

int array[EP100_LIB_MAX_X][EP100_LIB_MAX_Y]

but that doesnt set up a 2d array with the pixels or does it?

**matsp** · 10-14-2007

It sets up a 2D array - no, the array doesn't automatically contain pixels (or anything else for that matter). Isn't that what those functions are for?

--
Mats

**taurus** · 10-14-2007

ok could someone please have a look at this pseudocode i developed and comment on it:

Code:

Algorithm image

ep100lib.h

INTEGER width
INTEGER height
DOUBLE scroll
CHARACTER filename <-- NULL
output 'Welcome to my program'

	if argv[1] = -i
		output 'You have decided to invert the image'
		..CALL FUNCTION..

	elseif argv[1] = -h
		scroll <-- argv[2]
		filename <-- argv[3]

		ep100_lib_init()
		ep100_lib_open_image(filename)

		INTEGER data[EP100_LIB_MAX_X][EP100_LIB_MAX_Y]
		ep100_lib_get_data(data)

		width <-- ep100_lib_get_image_width()
		height <-- ep100_lib_get_image_height()

		output 'You have decided to scroll the image'
		
		
		scroll_image_procedure(data,scroll)

		
	elseif argv[1] = -v
		DOUBLE scroll <-- argv[2]
		output 'You have decided to scroll the image'
		..CALL FUNCTION..

	else 
		output 'ERROR: Incorrect argument'
		return 0
	endif
end algorithm

and the procedure:

Code:

void scroll_image_procedure(int data[EP100_LIB_MAX_X][EP100_LIB_MAX_Y], 						double scroll)

		INTEGER x
		for(x <-- 0 to Ep100_LIB_MAX_X)
			data[X+scroll] = data

thanks

**matsp** · 10-14-2007

When you scroll the image, how do you plan on dealing with "what's falling over the edge"? Does the image grow, or are you wrapping it around the end to the other side? Or is the scrolled image guaranteed to fit in the new data?

Also, are you allowed to scroll in multiple directions (horizontal, vertical, positive and negative amounts?)

All of the above should be covered in your requirements, or you can't really implement the function - but maybe you are allowed to interpret it as you like? If so, which are you trying to implement?

You scroll function probably should only scroll the ACTUAL width/height of the image, rather than the entire image size (assuming that is not the same thing - which I think it isn't, but again, I don't know).

--
Mats

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