#include <cs50.h> #include <ctype.h> #include <stdio.h> #include <stdlib.h> #include <string.h> int main(void) { FILE *file = fopen("phonebook.csv", "a"); string name = get_string("Name: "); string number = get_string("Number: "); fprintf(file, "%s,%s\n", name, number); fclose(file); }