Print the dump of a structure which will be useful for understanding structure padding

dump_struct.c

void dump_structure(void *ptr, unsigned long size) {
    unsigned long addr;

    // Top row of the table
    printf("\nSize of the structure: %lu\n                 ", size);
    for(int i = 0; i <= 0xf; i++) {
        if(i == 8) printf(" ");
        printf(" %x ", i);
    }

    // Horizontal seprator
    printf("\n---------------+--------------------------------------------------");

    for(int i = 0; i < size; i++) {
        addr = ((unsigned long)(ptr + i));

        if((i == 0) && (addr & 0xF)) {
            // Set the last digit of address as 0
            printf("\n0x%lx | ", addr & ~(0xF));

            // If the address is not starting from mod 16
            // Add padding with 00 till the data
            printf(" 00 00 00 00 00 00 00 00 ");
        }

        if(addr % 16 == 0) {
            // Print address after every 16 bytes
            printf("\n0x%lx | ", addr);
        }

        // A vertical line after 8 bytes
        if(addr % 8 == 0) printf(" ");

        // Print each bytes
        printf("%02x ", *(unsigned char*)(ptr+i));
    }

    printf("\n\n");
}

Call this function to print the structure data in the memory.

Sample code

#include <stdio.h>
#include <stdint.h>

typedef struct {
    int m;
    long f;
} datatype;


int main() {
    datatype data = {0x12345678, 6};
    dump_structure(&data, sizeof(data));
    return 0;
}

The output of above code will be

Shafeeques-MacBook-Air:tmp$ ./main

                 0  1  2  3  4  5  6  7   8  9  a  b  c  d  e  f
-------------+--------------------------------------------------
7ff7b979d720 |  78 56 34 12 00 00 00 00  06 00 00 00 00 00 00 00