Program to calculate number of VOWELS in a string

#include<stdio.h>
#include<iostream.h>
#include<conio.h>
void vowel(char a[]);
void main()
{
clrscr();
char a[10];
cout<<"enter a string";
gets(a);
vowel(a);
getch();
}
void vowel(char a[])
 {
  int i,count;
  for(i=0;a[i]!='\o';i++)
     {
      if(a[i]=='a'||a[i]=='e'||a[i]=='i'a[i]=='o'||a[i]=='u')

         count++;

     }
  cout<<"no. of vowels in a string are"<<count;
 }