// Pantea Aria

// strings - reading - working on chars one by one
// ctype.h library functions

// Write a C program that reads a line of characters from the user and 
// send it to a function, converts all uppercase letters to lowercase.

// can you write it for multiple books? until user enters Ctrl-D


#include <stdio.h>
#include <ctype.h>

#define MAX 30

void my_tolower(char str[]);
int main(void) {
    char book[MAX];  // means book is an empty string now

    // how can I repeat this?
    printf("Enter your favourite book: ");
    while (fgets(book, MAX, stdin) != NULL) {  
        
        printf("Original: %s", book);

        // call the function
        my_tolower(book);
        printf("Lowercase: %s", book);

        printf("Enter your favourite book: ");

    }
    return 0;
}
void my_tolower(char str[]) {
    int i = 0;
    while(str[i] != '\0' && str[i] != '\n'){
        str[i] = tolower(str[i]);
        i++;
    }
}