When is a function declared without a return type allowed?

A function declared without a return type is allowed when specified as void. In programming, particularly in languages like C, C++, and Java, the void keyword indicates that the function does not return any value to the calling function. This is useful when a function's purpose is to perform actions, such as modifying variables, printing output, or other side effects, without needing to send any data back through a return statement.

When a function has a return type of void, you call it simply for its side effects, rather than expecting a return value. This allows for cleaner and more organized code, especially when dealing with functions aimed at performing tasks rather than calculations or logic that provide outputs.

In contrast, declaring a function as an integer, character, or string implies that it is expected to return a value of that type, which would contradict the purpose of having a function that is meant to be void.