Using Pointers Count Vowels

#include <stdio.h>

int main()
{
    char str1[100],ch;
    char *ptr;
    int  vcount=0,ccount=0;
    printf("\n\n Using C Pointers : Count Vowels and Consonants :\n"); 
    printf("-----------------------------------------------------\n");	    
    printf(" Enter a string: ");
    gets(str1);
     
    /*store base address of str1 in to pointer ptr */
    ptr=str1;
     
    /* loop to iterate through the string characters */
    while(*ptr!='\0')
    {
        
        /*convert character to lowercase*/
        ch = tolower(*ptr);
		/* check and count vowels or consonants */
		if(ch=='a' ||ch=='e' ||ch=='i' ||ch=='o' ||ch=='u')
            vcount++;
        else if ( ch>='a' && ch<='z')  /*if it is an alphabet and not vowel*/
            ccount++;
        ptr++; /*point to next character */
    }
     
    printf(" Number of vowels : %d\n Number of consonants : %d\n",vcount,ccount);        
    return 0;
}