Works with cout.. but not with printf...???

[datta016]

Hey,
So I'm trying to write this simple program in which I create a struct that contains two string objects and an int. Through typedef I create an instance of the struct, initialize the 3 values, then print them. Following this, to better understand pointers I take the address of the values and assign it to a pointer to my struct, change the values, and then print them.

Immediately below is the output I get using cout <<, and it looks fine.

Hello
Goodbye
6
olleH
eybdooG
9
Press any key to continue . . .

I then tried, out of curiosity, to print it out using printf(), and I keep getting this Run Time Error:

PRE-POINTER:
(null)
Press any key to continue . . .

Below is my code. If someone could just take a glance and help me see if there is anything blatantly wrong with the way I'm using printf() or point out if the problem lies elsewhere, I would be greatly appreciative.

#include <stdio.h>
#include <iostream>
#include <string>
using namespace std;

typedef struct Structure1
{
	std::string str1;
	std::string str2;
	int int1;
} Structure1;

int main()
{
	Structure1 testStruct1;
	Structure1* testStruct2 = &testStruct1;
	
	testStruct1.str1 = "Hello";
	testStruct1.str2 = "Goodbye";
	testStruct1.int1 = 6;
	//cout << testStruct1.str1 << endl << testStruct1.str2 << endl << testStruct1.int1 << endl;
	printf("PRE-POINTER:\n%s\n%s\n%d\n\n", testStruct1.str1, testStruct1.str2, testStruct1.int1);

	testStruct2->str1 = "olleH";
	testStruct2->str2 = "eybdooG";
	testStruct2->int1 = 9;
	//cout << testStruct2->str1 << endl << testStruct2->str2 << endl << testStruct2->int1 << endl;
	printf("POST POINTER:\n%s\n%s\n%d\n", testStruct2->str1, testStruct2->str2, testStruct2->int1);

	return 0;
}

Thanks to all in advance.

[jsmith]

you are passing a non-POD type (std::string) through ellipsis.

you should be getting a compiler warning to that effect.

you want str1.c_str(), which returns a const char*, which is what %s expects.

(also str2)

[datta016]

Wow jsmith, to the rescue again!

That's pretty cool. Prior to this I was completely ignorant to *.c_str(). Now I've learned something new.

Works perfectly now. Thank you again!