typedef struct book {
char title[20];
char author[20];
int pages[10];
} Book;
Book b1 = {"The Zahir","Paulo Coelho",336,0};
while writing this structure into SPIFFS of ESP8266, I am using function
filename.write( (const uint8_t*)&b1, sizeof(b1));
but how can write a single data like name of book into structure of spiffs?
For this kind of situation it's best to treat your data as records in a database. To change one part of a record you read the entire record, change the value, then write that record back.
int record = 4; // which record you want to change
struct book b; // Temporary storage for editing the data
// Go to the record and read it in
filename.seek(record * sizeof(struct book));
filename.read( (const uint8_t*)&b, sizeof(struct book));
// Change the data
strcpy(b.title, "Winnie The Pooh");
// Go to the record again and write it out
filename.seek(record * sizeof(struct book));
filename.write( (const uint8_t*)&b, sizeof(struct book));
