rev_case.c

#include <stdlib.h>

#define lc(var) (var >= 'A' && var <= 'Z' ? var + 32 : var)
#define uc(var) (var >= 'a' && var <= 'z' ? var - 32 : var)
#define vowelp(var) ( \
    uc(var) == 'A' || \
    uc(var) == 'E' || \
    uc(var) == 'I' || \
    uc(var) == 'O' || \
    uc(var) == 'U')

char *rev_case (char *str) {
    int i = 0;
    int len = 0;
    char *curr = str;
    char *ret = NULL;
    while (*(curr++)) len++;
    ret = (char *)malloc(sizeof(char)*len);
    for (i = 1; i <= len; i++) {
        ret[len-i] = vowelp(str[i-1]) ? uc(str[i-1]) : lc(str[i-1]);
    }
    ret[i] = '\0';
    return ret;
}

rev_case.pl

sub rev_case {map {tr/A-Z/a-z/;tr/aeiou/AEIOU/;scalar reverse $_} @{[@_]}}

rev_case.py

from string import maketrans
def rev_case(s):
    return s.lower().translate(maketrans("aeiou","AEIOU"))[::-1]

rev_case.sh

function rev_case { tr A-Z a-z | tr aeiou AEIOU | rev ; }