Printing the structure using a single line in C?

Question

Is there any possible way in C (by using any function or any such kind) so that we can print the contents in a structure of different datatypes using a single line? Say for eg:

typedef struct ABC{
   int a;
   char b;
   long c;
}ABC1;

To print this we need to write: printf("%d %s %ld",ABC1.a,ABC1.b,ABC1.c)

Any other method so that i can print like printf("????",????ABC1)??

Answer 1

Glibc allows you to establish your own format specifiers for printf and family to let you print UDTs, which would not otherwise be possible, through some extensions.

#include <stdio.h>
#include <printf.h> /* For PA_POINTER */

struct MyStruct
{
    int a;
    double b;
};

struct print_info;
int handler(FILE *stream, const struct print_info *i, 
        const void* const *args)
{
    const struct MyStruct *ptr = *( (const struct MyStruct**) (*args) );
    int rc = fprintf(stream, "a: %d, b: %f\n", ptr->a, ptr->b);

    return rc;
}

int print_arginfo (const struct printf_info *info, size_t n,
                      int *argtypes)
{
  if (n > 0)
    argtypes[0] = PA_POINTER;
  return 1;
}

int main(void)
{
    struct MyStruct s = {55, -3.14};
    /* We're gonna use the M specifier */
    int spec = 'M';
    int rc = register_printf_function(spec, handler, print_arginfo);

    if (rc != 0)
        return 1;

    printf("%M", &s);

};

You may find the documentation here.