C :

fuzhi(a,b)
char a[100],b[100];
{int i,j=0;
for(i=0;a[i]!='\0';i++)
if(a[i]==97||a[i]==101||a[i]==105||a[i]==111||a[i]==117||a[i]==65||
a[i]==69||a[i]==73||a[i]==85) {b[j]=a[i];j++;}

b[j]=0;
}
int main()
{char str1[100],str2[100];
scanf("%s",str1);
fuzhi(str1,str2);
printf("%s",str2);
}

C++ :

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
int main()
{
char i[10000];
cin>>i;
int n;
n=strlen(i);
for(int q=0;q<n;q++)
{
        if(i[q]=='a') cout<<i[q];
        if(i[q]=='e') cout<<i[q];
        if(i[q]=='i') cout<<i[q];
        if(i[q]=='o') cout<<i[q];
        if(i[q]=='u') cout<<i[q];
}
cout<<endl;
return 0;
}

Java :

import java.util.Scanner;

public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner input = new Scanner(System.in);
		
		String s = input.next();
		for(int i = 0; i < s.length(); i ++){
			if(s.charAt(i) == 97 || s.charAt(i) == 101 || s.charAt(i) == 105 || s.charAt(i) == 111 || s.charAt(i) == 117){
				System.out.print(s.charAt(i));
			}
		}
		//System.out.printf("%.3f",area);
		input.close();
	}
	
	

}

Python :

a = map(lambda x:(x), raw_input().split())[0]

#b = a[1]
#c = a[2]
#a = a[0]

import re
p = re.compile('[aeiou]')
l = re.findall(p,a)
x=''
for i in l :
    x+=i
print x