How are long integers declared in C++ to ensure proper type interpretation?

In C++, long integers can be declared using the long keyword. To ensure proper type interpretation, you can also specify whether the integer is signed or unsigned. Here are some examples of how to declare long integers:

Signed long (default is signed):
```
long myLong = 1234567890;
```

Unsigned long:

unsigned long myUnsignedLong = 1234567890;

Long with explicit size (using long long for larger values):
```
long long myLongLong = 1234567890123456789;
```

Unsigned long long:

unsigned long long myUnsignedLongLong = 1234567890123456789;

Using these declarations ensures that the variables are interpreted correctly as long integers, and you can choose between signed and unsigned types based on your needs.