A simple look at what can happen when you don't use pointers correct

struct_pointer.c

#include <stdio.h>

typedef struct
{
    char rgbtBlue;
    char rgbtGreen;
    char rgbtRed;
    char int_padding;
} __attribute__((__packed__))
RGBTRIPLE;

int main(void) {

    // lets create an RGBTRIPLE with a little data
    // this doesn't mean anything, but we will use
    // this in order to understand how pointers
    // look at the data in the struct
    RGBTRIPLE test_subject = {1, 2, 3, 0};

    // Notice using these statements here the addresses line up
    // sequentially in memory. This is how a struct is created
    // in computer memory.
    // Notice how the numbers are what we would expect them to be
    printf("ts value b = %i | at addr %p\n", test_subject.rgbtBlue, &test_subject.rgbtBlue);
    printf("ts value g = %i | at addr %p\n", test_subject.rgbtGreen, &test_subject.rgbtGreen);
    printf("ts value r = %i | at addr %p\n", test_subject.rgbtRed, &test_subject.rgbtRed);
    printf("\n");
    // Above in the RGBTRIPLE struct, notice I added
    // an extra value in there. This is due to the size
    // of an int, and how a pointer to that struct would
    // look at the memory. So lets go ahead and make a
    // mistake
    int* mistake = (int*)&test_subject.rgbtBlue;
    *mistake = 12345; // This is the mistake here
    
    // So what happened to our test subject?
    // I took the address of test_subject as a pointer of size int
    // Then just wrote over all them memory that exists there
    // Lets see what would print out now having done so...
    printf("ts value b = %i | at addr %p\n", test_subject.rgbtBlue, &test_subject.rgbtBlue);
    printf("ts value g = %i | at addr %p\n", test_subject.rgbtGreen, &test_subject.rgbtGreen);
    printf("ts value r = %i | at addr %p\n", test_subject.rgbtRed, &test_subject.rgbtRed);
    printf("\n");
    
    // Notice now nothing makes sense. Everything has become
    // garbage because of my mistake. We need to make sure
    // and be careful that we know what we are looking at
    // using pointers.

    // How do we solve this problem?
    // Remember the size of the memory address that we
    // are pointing to is important. So lets try again.
    test_subject = (RGBTRIPLE){1, 2, 3, 0};    
    char* not_mistake = &test_subject.rgbtBlue;
    *not_mistake = 127;
    not_mistake++;
    *not_mistake = 126;
    not_mistake++;
    *not_mistake = 125;

    // Here I just made sure the size of the point is equivalent
    // to the size of the data in the struct and changed it
    // Does it make sense now?

    printf("ts value b = %i | at addr %p\n", test_subject.rgbtBlue, &test_subject.rgbtBlue);
    printf("ts value g = %i | at addr %p\n", test_subject.rgbtGreen, &test_subject.rgbtGreen);
    printf("ts value r = %i | at addr %p\n", test_subject.rgbtRed, &test_subject.rgbtRed);
    printf("\n");

    // Looks correct to me.
    return 0;
}