Question

The following code snippet generates some warning messages when compiling:

Cluster& Myclass::getCluster(const Point &p)
{
    foreach (Cluster c, *this)
        foreach (Point point, c)
            if (point == p)
                return c;
}

The warnings are:

1. reference to local variable ‘c’ returned [enabled by default]
2. control reaches end of non-void function [when using -Wreturn-type]

I know that I am not returning a value if the condition fails. However, when I try return 0 it gave me error.

How can I solve these issues?

Answer 1

If your function can legitimately fail to find a matching Cluster, then you should have it return a pointer:

Cluster* Myclass::getCluster(const Point &p)
{
    foreach (Cluster c, *this)
        foreach (Point point, c)
            if (point == p)
                return &c;
    return 0; // or return nullptr; in C++11
}

But this doesn’t work yet, because c is a local variable. So you make it a reference, like this:

Cluster* Myclass::getCluster(const Point &p)
{
    foreach (Cluster& c, *this)
        foreach (Point point, c)
            if (point == p)
                return &c;
    return 0; // or "return nullptr;" in C++11
}