How to reset this string scanning code for a new letter?

Question

I'm in the middle of homework and nearly finish. This is my code

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

void main()
{
    char word[100],*ptr,input;
    int count,i,n;
    printf("Enter the word : ");
    scanf("%[^\n]", word);
    ptr = &word;
    do
    {
        printf("Enter the letter : ");
        scanf(" %c", &input);
        if(input == '-'){
                printf("Exit.");
                return 0;
        }
        for(i=0;word[i] != '\0';i++)
        {
            if(*ptr == input)
                count++;
            ptr++;
        }
        printf("Has %d of '%c'",count,input);
        printf("\n");
    }while(input != '-')
}

This code will extract the number of letter in string

For example : If you input "WWWWooo" it will give you "has 4 of 'W'" and "has 3 of 'o'"

Code will exit when you put '-' letter.

Problem that I find is the 'count' value seems to remain the total of number of the first letter I want to find.

What I expect : "WWWWooo" will give "has 4 of 'W'" and "has 3 of 'o'"

What I get is "has 4 of 'W'" and "has 4 of 'o'". The count value didn't reset.

I tried to put count = 0; on the top of do while loop and the output will always be 0 for the second letter scanned for.

How can I fix this?

Answer 1

I changed your code a bit, I guess this is what you're looking for (the comments in the code explain pretty much all the changes I've made):

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

int main(void)
{
    char word[100],*ptr,input;
    int count,i,n;
    printf("Enter the word : ");
    scanf("%99[^\n]", word); //changed to %99[^\n] to avoid buffer overflows
    do
    {
        count=0; //count=0 should be here as count++ changes the value of count afterwards
        ptr=word; //ptr=word should be here too since ptr++ changes the value of ptr afterwards
        /* you might have probably gotten a compiler warning because
        of ptr=&word, since &word is char(*)[100] (a pointer to an array of 100 chars)
        and char(*)[100] and char * are quite different,
        so you can either do ptr=word or ptr=&word[0] (both of which point to the first character in the array) */
        //the rest of the code below is basically the same
        printf("Enter the letter : ");
        scanf(" %c", &input);
        if(input == '-'){
                printf("Exit.");
                return 0;
        }
        for(i=0;word[i] != '\0';i++)
        {
            if(*ptr == input)
                count++;
            ptr++;
        }
        printf("Has %d of '%c'",count,input);
        printf("\n");
    }while(input != '-'); //you had missed a ';' here
}

The int main(void) is because, quoting n1570 (emphasis mine):

It shall be defined with a return type of int and with no parameters: int main(void) { /* ... */ } or with two parameters (referred to here as argc and argv, though any names may be used, as they are local to the function in which they are declared): int main(int argc, char *argv[]) { /* ... */ } or equivalent

Even though I haven't checked the return value of scanf() in the above code, but as mentioned by @Yunnosch in the comment, it's always a good idea to do so.