What will be the output of the program?

#include<stdio.h>
void fun(int);
typedef int (*pf) (int, int);
int proc(pf, int, int);

int main()
{
    int a=3;
    fun(a);
    return 0;
}
void fun(int n)
{
    if(n > 0)
    {
        fun(--n);
        printf("%d,", n);
        fun(--n);
    }
}

#include<stdio.h>

int main()
{
    int arr[5], i=0;
    while(i<5)
        arr[i]=++i;

    for(i=0; i<5; i++)
        printf("%d, ", arr[i]);

    return 0;
}

#include<stdio.h>
#include<math.h>
int main()
{
    float a=5.375;
    char *p;
    int i;
    p = (char*)&a;
    for(i=0; i<=3; i++)
        printf("%02x\n", (unsigned char)p[i]);
    return 0;
}

#include<stdio.h>
int main()
{
    int i=2;
    printf("%d, %d\n", ++i, ++i);
    return 0;
}

#include<stdio.h>
#include<stdlib.h>

int main()
{
    char *i = "55.555";
    int result1 = 10;
    float result2 = 11.111;
    result1 = result1+atoi(i);
    result2 = result2+atof(i);
    printf("%d, %f", result1, result2);
    return 0;
}

#include<stdio.h>
const char *fun();

int main()
{
    char *ptr = fun();
    return 0;
}
const char *fun()
{
    return "Hello";
}

#include<stdio.h>
#include<stdarg.h>

int main()
{
    void display(char *s, int num1, int num2, ...);
    display("Hello", 4, 2, 12.5, 13.5, 14.5, 44.0);
    return 0;
}
void display(char *s, int num1, int num2, ...)
{
    double c;
    char s;
    va_list ptr;
    va_start(ptr, s);
    c = va_arg(ptr, double);
    printf("%f", c);
}