#include <kernwin.hpp> // For get_screen_ea() et al
#include <bytes.hpp>

// Prompt the user for an address, then a string
ea_t addr = get_screen_ea();
askaddr(&addr, "Address to put string:");
char *string = askstr(0, "", "Please enter a string");

// Write the user supplied string to the address the user specified.
patch_many_bytes(addr, string, strlen(string));