Help reading a jpeg file into frames of 100 bytes!! :S

[rodiannef]

Hey,

I am trying to do a small part of the assignmet given to me, but cannot manage to get it to work.

I want to open a jpeg file which already exists.. and then convert it into streams of 100 bytes of code (frame). Upon running the following program, nothing happens?! :S I have no idea what is happening..

A window pops up saying:

"An unhandled exception of type 'System.NullReferenceException' occured in 'TryOut.exe.
Additional Information: Object reference not sent to an instance of an object."

The following is the code:

#include <stdio.h>

int main (void)
{

	unsigned char frame[100], plz;
	int i;

	FILE *cfPtr;
	
	if((cfPtr = fopen("C:/Documents and Settings/photo1.jpg", "rb") == NULL))
	{
		printf("File could not be opened\n");
        scanf("%d\n\n", &plz);
	}

	else
	{
		while (!feof(cfPtr))
		{
			for(i = 1; i <= 100; i++)
			{
                fread(&frame[i], sizeof(char),1,cfPtr);
				printf("%d\n", frame[i]);
				scanf("%d\n\n", &plz);
			}
		}
				fclose(cfPtr);
	}
	return 0;
}

[Adak]

#include <stdio.h>

int main (void)
{

	unsigned char frame[100], plz;
	int i;

	FILE *cfPtr;
	
	if((cfPtr = fopen("C:/Documents and Settings/photo1.jpg", "rb") == NULL))
	{
		printf("File could not be opened\n");
               scanf("&#37;d\n\n", &plz);
	}

	else
	{
		while (!feof(cfPtr))
		{
			for(i = 1; i <= 100; i++)
			{
                                fread(&frame[i], sizeof(char),1,cfPtr);
				printf("%d\n", frame[i]);
				scanf("%d\n\n", &plz);
			}
		}
		fclose(cfPtr);
	}
	return 0;
}

Your indentation is manic, but anyway, you're over-running the frame[]. C arrays go from 0 to array size - 1, not 1 to array size. Also, you're using %d in printf(), which should be %c, for a char.

[rodiannef]

Yes you have a point! .. I didn't see that one!

Do you know why it is printing numbers instead of binary from the array frame?

Thanks for you help

#include <stdio.h>

int main (void){

	unsigned char frame[100];
	int i;

	FILE *cfPtr;
	
	if((cfPtr = fopen("C://Documents and Settings//photo1.jpg", "rb")) == NULL){
		printf("File could not be opened\n");
	}

	else{
		while (!feof(cfPtr)){
			for(i = 0; i <= 99; i++){
                fread(&frame[i], sizeof(char),1,cfPtr);  /*reads byte byte*/
				printf("&#37;c\n", frame[i]);
			}
		}
		fclose(cfPtr);
	}
	return 0;
}

[tabstop]

What is binary, if not numbers? printf doesn't have a %thingy for printing in binary. You can do oct or hex if you want.

[Salem]

Try this

while ( fread(frame, sizeof(char),sizeof(frame),cfPtr) > 0 ) {
  // for loop here
}