promijeni samoglasniek velika/mala

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

char * funkcija(char *s, char nova[])
{
    char*p=nova;


    while(*s!='\0')
    {

        if(*s=='a' ||*s=='e' ||*s=='i' ||*s=='o' ||*s=='u')
        *p=*s -32;

        else if(*s=='A' ||*s=='E' ||*s=='I' ||*s=='O' ||*s=='U')
            *p=*s + 32;

        else *p=*s;
        p++;
        s++;

    }
    *p='\0';
    return nova;

}






int main()
{
    char rec[100]={"Avion"};
    char nova[100];
    char*p;
    p=nova;
    p=funkcija(rec, nova);
    while(*p!='\0')
    {
        printf("%c", *p);
        p++;
    }

}