printf() surprising console output

Question

I need to develop with C++ after a break of a few years. Anyway, I got problems following the tutorials I am currently reading. After writing the following code-snippet I expected to see 'Hello World' in my console, but I am only able to see 'Debug: StrangeChars'; What went wrong?

std::string myString("Hello World"); 
printf("* Debug: %s \n", myString);

Solution 1

printf relies on you passing the right arguments. %s requires a char *, you passed a std::string.

Try (C way)

char myString[] = "Hello World";
printf("* Debug: %s \n", myString);

Or (Hybrid C/C++ way)

std::string myString("Hello World"); 
printf("* Debug: %s \n", myString.c_str());

Or the C++ way:

std::string myString("Hello World"); 
std::cout << "* Debug " << myString << std::endl;

Solution 2

Try

printf("* Debug %s \n", myString.c_str());

or better still:

std::cout << "* Debug " << mystring << std::endl;

Solution 3

The string type referenced by printf's %s% is not the same as std::string.

In fact, when printf was specified, std::string did not even exist. In C++ you should use std::cout instead, which works as expected:

#include <iostream>
 [...]

std::string myString("Hello World"); 
std::cout << "* Debug: " << myString << " \n";

Comments

[Bret Kuhns]

+1 for the "C++ way". The other two options should be ignored, IMO.

[Sergey L.]

@BretKuhns The question originally also had the C tag which someone removed.