#include <stdio.h>

void main()
{
    struct solarsystem {
        char planet[8];
        double population;
    };

    struct solarsystem planets[9] = {
        "Mercury", 0,
        "Venus", 0,
        "Earth", 5.5E9,
        "Mars", 0,
        "Jupiter", 0,
        "Saturn", 0,
        "Uranus", 0,
        "Neptune", 0,
        "Pluto", 0
        };
    struct solarsystem temp;

    int x;

    puts("Solar System Data");

    for(x=0;x<9;x++)
        printf("Planet %i: %s, Population: %.0f\n",\
            x+1,
            planets[x].planet,
            planets[x].population);

    puts("\nAfter we swap with Jupiter:");

/* Copy Jupiter's data to temp */

    temp = planets[4];

/* Copy Earth to Jupiter */

    planets[4]= planets[2];

/* Copy temp to Earth */

    planets[2]=temp;

    for(x=0;x<9;x++)
        printf("Planet %i: %s, Population: %.0f\n",\
        	x+1,
            planets[x].planet,
            planets[x].population);
}