Input a string character by character

I am trying to take input a string character by character. At the end of loop I am asking if the user want to continue entering into string. Code below is not producing desired output.

Please tell me the error.

#include<stdio.h>
#include<stdlib.h>

int main()
{
    char str[100], ch= 'y';
    int i=0;

    while(ch =='y' )
        {
        printf("\nEnter a character ");
        scanf("%c", &str[i]);
        i++;

        printf("\nDo you want to continue entering ");
        scanf("%c", &ch);
        }
    return 1;
}