Problums writeing struct to a file C++

[dreamvb]

hi all, C++ beginner needs help.

I decided today to give C++ FileIo Streams a little go. since I not played with them much before and have not started out very well

anyway I desided to make a little project that can save the contents of a struct to a file. pretty basic in fact.

My problum is reading back the info. the letter and number displays ok but for some reason str is not. anyway I left my code below if that helps.

#include <iostream>
#include <fstream>
using namespace std;
 
struct test
{
    int number;
    char letter;
    char *str;
} aTest;
 
 
int main(int agvc)
{
    ofstream fout;
    ifstream fin;
    // fill struct with some random data
    aTest.number = 245;
    aTest.letter = 'A';
 
    //What am I doing wrong here I wonder
    aTest.str = (char*) malloc(100);
    strcpy(aTest.str,"Hello World this is a long string");
 
 
    //write the struct to the file
    
    fout.open("C:\\test.txt",ios::binary);
    fout.write((char*)(&aTest),sizeof(aTest));
    fout.close();
    
    // Clear struct of it's data I am only new in C++
    // So i am not sure this is the correct way to clear stuff out
    // tho for the example it be ok I think
    aTest.letter = '\0';
    aTest.number = 0;
    strcpy(aTest.str,"\0");
    //Load the struct back in so we can display the data
 
    fin.open("c:\\test.txt",ios::binary);
    fin.read((char*)(&aTest),sizeof(aTest));
    fin.close();
 
    // display the data
    std::cout << "Number: " << aTest.number << "\n";
    std::cout << "Letter: " << aTest.letter << "\n";
    std::cout << "String: " << aTest.str << "\n"; // :( why is my str not showing
 
}

anyway hope someone can help
Thanks.