a.out issue

[Vy C]

Hello everyone,

New to C++, I have a program that i created and every time I run my a.out it produces my answer, but put a "?" at the end of my output.

What am I doing wrong???

#include<iostream>

using namespace std;

int main()
{
char myWords[4] = {'a','b','y','z'};
cout << myWords << endl;
return 0;
}

a.out = abyz?

[DSLq5Di1]

What you have there is not a c-string, but an array of characters.
http://en.wikipedia.org/wiki/Null-terminated_string

You could output the characters individually cout << myWords[0] << myWords[1] << etc, append a null character to the end char myWords[5] = { ... , '\0' };, or initialize the array with a string literal (implicit null) char myWords[] = "abyz";.

[freddy92]

Well when I ran your code, it just output "abyz" with no "?", so I'm guessing it's related to your compiler.

[Vy C]

That's the part I don't get, because a friend at school typed the same exact thing and it didn't give him the "?".

I understand what sloppy is saying, but I would like to know why it works this way with some and not with others.

[Peter87]

When you output myWords it will print all characters until it finds a null character '\0'. You don't have a null character in the array so it will continue read outside the array. This memory might belong to other variables and such things, depending on what the compiler puts there.

[DSLq5Di1]

You'll see whatever resides in memory after your array of characters, this may be nothing, or it may be something, cout will continue printing characters until a null terminator is encountered.

For an example,

#include <iostream>
using namespace std;

struct example
{
        static char hello[];
        static char garbage[];
};
// I'm using a struct to ensure hello and garbage are
// contiguous in memory (assuming there is no padding).

char example::hello[] = { 'H', 'e', 'l', 'l', 'o' }; // array of characters
char example::garbage[] = "????"; // null terminated string

int main()
{
        cout << example::hello;
        return 0;
}

Hello????

[Vy C]

Thanks you sloppy, makes sense.

Appreciate all the feed back.