'read': identifier not found, short code plz help

[chopficaro]

im just trying to get the hang of binary file io by making a simple program that can write a structure into a file, then read it, but the first error message i get is

'read': identifier not found

heres the code:

code:

#include <iostream> #include <fstream> using namespace std; struct grades { int grade1; int grade2; int grade3; int grade4; } mygradesi,mygradeso; int main () { int answer; do { cout<<"do u want to 1, write to the file or 2, read from the file, or 3, exit the program?"; cin>>answer; if (answer==2) { struct grades * mygradesptri; mygradesptri=&mygradesi; ifstream myfilei; myfilei.open ("binary.bin", ios::in|ios::binary); if (myfilei.is_open()) { read(mygradesptri, sizeof(grades)); cout<< mygradesi.grade1<< mygradesi.grade2<< mygradesi.grade3<< mygradesi.grade4; } else cout << "Unable to open file for input"; } if (answer==1) { struct grades * mygradesptro; mygradesptro=&mygradeso; ofstream myfileo; myfileo.open ("binary.bin", ios::out|ios::binary); cout>>"please enter 4 grades"; cin<< mygradeso.grade1<< mygradeso.grade2<< mygradeso.grade3<< mygradeso.grade4; if (myfileo.is_open()) { write (mygradesptro, sizeof(grades)); myfileo.close(); } else cout << "Unable to open file for output"; } }while (answer!=3); return 0; }

[chopficaro]

how silly of me, i did not specify the name of the class. i ran into a new problem though, read and write are supposed to take char *, but im not trying to pass a char, im trying to pass a structure pointer, how do i do that?

error says cannot convert grades * to char *

code:

#include <iostream> #include <fstream> using namespace std; struct grades {         int grade1;         int grade2;         int grade3;         int grade4; } mygradesi,mygradeso; int main () {         int answer;         do         {                 cout<<"do u want to 1, write to the file or 2, read from the file, or 3, exit the program?";                 cin>>answer;                 if (answer==2)                 {                         char * mygradesptri;                         mygradesptri=&mygradesi;                         ifstream myfilei;                         myfilei.open ("binary.bin", ios::in|ios::binary);                         if (myfilei.is_open())                         {                                 myfilei.read(mygradesptri, sizeof(grades));                                 cout<< mygradesi.grade1<< mygradesi.grade2<< mygradesi.grade3<< mygradesi.grade4;                         }                         else cout << "Unable to open file for input";                 }                 if (answer==1)                 {                         char * mygradesptro;                         mygradesptro=&mygradeso;                         ofstream myfileo;                         myfileo.open ("binary.bin", ios::out|ios::binary);                         cout>>"please enter 4 grades";                         cin<< mygradeso.grade1<< mygradeso.grade2<< mygradeso.grade3<< mygradeso.grade4;                         if (myfileo.is_open())                         {                                 myfileo.write (mygradesptro, sizeof(grades));                                 myfileo.close();                         }                         else cout << "Unable to open file for output";                 }         }while (answer!=3);         return 0; }

[OneOffDriveByPoster]

chopficaro @ Tue Sep 02, 2008 11:46 am wrote:

how silly of me, i did not specify the name of the class. i ran into a new problem though, read and write are supposed to take char *, but im not trying to pass a char, im trying to pass a structure pointer, how do i do that?

IIRC, you can cast the grades* to char* in the call to read() and it should work fine.

[chopficaro]

brilliant! TY! works great!