Unsigned Char is (null) after reading the binary file into the same - c

Question

I have to open/read a file which is an ascii art file (image)
and requires me to return the width and height of the image to the main routine and then requires me to pass the picture data back via a pointer. Here is the function prototype that I MUST use:
unsigned char *foo(char *filename, int *width, int *height)
Inside of foo, I must use a dynamic array of chars
to store tha image data. I need to use fread() to read
that data. I must also account for the carriage return at the end of each line.
Once I have opened and read the data, pass it back to the main routine. The main routine must then create a dynamic 2D array to store the image, copy the 1D array
into the 2D array, and display the image on the screen.
Image File Name: data.txt
My Code:
#include <stdio.h>
#include <stdlib.h>
void readDimension(FILE *inFile, int *width, int *height)
{
int i;
for (i = 0; i < 2; i++)
{
if (i == 0)
{
fscanf(inFile, "%d", width);
}
if (i == 1)
{
fscanf(inFile, "%d", height);
}
}
}
unsigned char *foo(char *filename, int *width, int *height)
{
FILE *inFile = fopen(filename, "rb");
readDimension(inFile, width, height);
unsigned char *ret = malloc(*width * *height);
fread(ret, 1, *width * *height, inFile);
fclose(inFile);
return ret;
}
int main(int argc, char** argv)
{
FILE *inFile;
int width, height;
unsigned char art;
if (argc == 1)
{
printf("Please specify a file name.\n");
}
else if (argc == 2)
{
inFile = fopen(argv[1], "rb");
if (inFile != NULL)
{
fclose(inFile);
art = foo(argv[1], &width, &height);
int n = sizeof(art);
printf("Data in Array: \\%c \n", art);
printf("Size of Array: %d \n", n);
}
else
{
printf("Error: File Not Found %s", argv[1]);
}
}
printf("Width: %d\n", width); // Testing
printf("Height: %d\n", height); // Testing
}

Answer 1

The problem is that you are trying to get the size of art, which is a pointer. It has fixed size. Size should be computed as width*height:
printf("Size of Array: %d x %d (%d)\n", width, height, width*height);
You declared art as an unsigned char, but you are assigning it a pointer to unsigned char. This is incorrect: art should be declared with an asterisk.
You are also printing a single character %c while passing an array art. This is not going to print anything of interest. If you wish to print the first character, print art[0]. If you wish to print the entire picture, make a pair of nested loops that iterate over the width and height, print each character, and print '\n' after each line.
Here are a few additional notes:
You should not read the entire file in one go with fread, because it would introduce \ns into the data. Instead, you should read the file line by line.
You can read width and height in the same function that reads the data
You do not need a loop to read two integers. You can do it in a single line, like this: fscanf(inFile, "%d %d", width, height);