Runtime Errors
- What does NullPointerException mean in Java?
A NullPointerException (NPE) in Java occurs when you try to use a reference variable that points to null, such as calling a method or accessing a field on it. It means the object you expected doesn't exist. - How do I fix IndexError: list index out of range in Python?
This error means you tried to access a list element at an index that doesn't exist. Check the list length, adjust your index, or use a safer method like a loop or slicing. - What does TypeError: 'NoneType' object is not subscriptable mean?
This error means you tried to use square bracket indexing on a variable that is None. In Python, None is not a container, so you cannot do something like x[0] if x is None. - Why do I get a segmentation fault in C?
A segmentation fault in C occurs when your program tries to access memory it doesn't have permission to access. Common causes include dereferencing null or uninitialized pointers, buffer overflows, and stack overflows. - What does ValueError: could not convert string to float mean?
It means Python tried to turn a string into a floating-point number, but the string wasn't a valid number (e.g., contained letters or symbols). - How do I fix a stack overflow error?
A stack overflow happens when a program uses too much call stack space, usually from infinite recursion or very deep recursion. Fix it by adding a base case, converting recursion to iteration, or increasing the stack size.