Final answer:
Giving a class member private access restricts its visibility to only within the defining class, supporting encapsulation and leading to better code maintenance and fewer errors.
Step-by-step explanation:
The effect of giving a class member private access in object-oriented programming is that the member is accessible only within the class it is defined. This means that the member cannot be accessed directly from outside of the class; not even derived classes (subclasses) can access private members of their parent classes. Using private access for members is a fundamental aspect of the principle of encapsulation, which is one of the four pillars of object-oriented programming.
Encapsulation provides a way to protect the data within a class from unintended use or manipulation by outside code, ensuring a tight control over how the data is accessed or modified. This leads to better maintenance and understanding of the code, as well as reducing the risk of errors caused by unintended interactions with the class members. It is recommended to make class members private by default and only expose what is necessary through public methods, also known as getter and setter methods.