Could you post your code?

I have never seen a function running without being called. The code would help us understand.

Additionally, try putting a breakpoint in the function and look through the call stack to see why the function is called.

I really doubt it's being run without being called, but it might be a more obscure call that you don't see right away.

You can't create local functions in C++. (Although lambdas are similar, but that's not what you are trying to do so forget about that)

void function();

just declares the function prototype (the semicolon at the end gives it away).

I think you are confused...

My program has SFML so I am not going to post that code but here is simple version of what I mean

#include <iostream>

using namespace std;

void function()
{
    cout << "Hello world!" << endl;
}

int main()
{
    return 0;
}

The program will say Hello World

but I want it to only run when i call the function later on

How do I stop that?

That's how you prevent it anyway.

Alternatively:

#include <iostream>
 
void myFunction(); //Declaration, allows main function to call this if it wants to, even though definition isn't here.
 
using namespace std;
 
int main()
{
 
    return 0;
}
 
void myFunction() //Definition
{
    cout << "Hello world!" << endl;
}

My program has SFML so I am not going to post that code but here is simple version of what I mean

#include <iostream>

using namespace std;

int main()
{
    void function();
    {
        cout << "Hello world!" << endl;
    }

    return 0;
}

The program will say Hello Worldbut I want it to only run when i call the function later onHow do I stop that?

My program has SFML so I am not going to post that code but here is simple version of what I mean

#include <iostream>

using namespace std;

int main()
{
    void function();
    {
        cout << "Hello world!" << endl;
    }

    return 0;
}

The program will say Hello World
but I want it to only run when i call the function later on
How do I stop that?

I see the problem, as previously noted by Paradigm Shifter and Washu, you're not coding a "function inside main".
What you are doing is declaring a function:

void function(); // Notice that ";", it marks the end of the function declaration

and then adding "Hello World!" to cout.

{
    cout << "Hello World!" << endl;
}

the { and } are just block separators, that you can use to limit scopes, between some other things.
So the function and the { cout } aren't related by any means.