Find no. of vowels in a string in C

#include<stdio.h>
void strcount(char []);
void main()
{
  char str[50];
  char c;
  while(1)
  {
    printf("enter string\n");
    //gets(str);
    scanf("%s",str);
    strcount(str);

    printf("want to run again? press y/n \n");
    scanf("%s",&c);
    if(c == 'n' || c == 'N')
        break;
  }
}
void strcount(char str[50])
{
int i,j=0;
for (i=0;str[i]!=NULL;i++)
 {
  if( str[i]=='a'||str[i]=='A'||str[i]=='e'||str[i]=='E'||str[i]=='i'||str[i]=='I'||str[i]=='o'||str[i]=='O'||str[i]=='u'||str[i]=='U')
  j++;
 }
 printf("count of vowels in string is %d\n",j);
}