C :

#include <stdio.h>

int main()
{
	char a[100];
	char b;
	int i,j;
	for (i=1;;i++)
	{
		b = getchar ();
		if (b!='\n')
		{
		   a[i] = b;
		}
		else
		{break;}
	}
	for (j=1;j<i;j++)
	{
		if (a[j]=='a' ||a[j]=='e' ||a[j]=='i' ||a[j]=='o' ||a[j]=='u')
		{printf("%c",a[j]);}
	}
	printf ("\n");
	return 0;
}

C++ :

#include<stdio.h>
int main()
{
	void cpy(char[], char[]);
	char str[80], c[80];
	gets(str);
	cpy(str, c);
	printf("%s\n", c);
	return 0;
}

void cpy(char s[], char c[])
{
	int i, j;
	for (i = 0, j = 0; s[i] != '\0'; i++)
		switch (s[i])
	{
		case 'A':c[j] = s[i], j++; break;
		case 'a':c[j] = s[i], j++; break;
		case 'E':c[j] = s[i], j++; break;
		case 'e':c[j] = s[i], j++; break;
		case 'I':c[j] = s[i], j++; break;
		case 'i':c[j] = s[i], j++; break;
		case 'O':c[j] = s[i], j++; break;
		case 'o':c[j] = s[i], j++; break;
		case 'U':c[j] = s[i], j++; break;
		case 'u':c[j] = s[i], j++; break;
	}
	c[j] = '\0';
}

Pascal :

var st:string;
    i:longint;
begin
  readln(st);
  for i:=1 to length(st) do
  if (st[i]='a') or (st[i]='e') or (st[i]='i') or (st[i]='o') or (st[i]='u') then 
  write(st[i]);
end.