Briefly explain what undefined behaviour is in the C programming language. Under what circumstance(s) would calling the following C function result in undefined behaviour? (2 marks) int divide(int *a, int *b) { return *a / *b; }

在 C 编程语言中，未定义行为是指程序的行为在语言规范中并未明确定义。

如果调用下面的 C 函数，在以下情况下会导致未定义行为：

1. 当 *b 的值为 0 时，除以 0 是不允许的，将导致未定义行为。

2. 当 *a 的值是最小整数值，并且 *b 的值是 -1 时，结果将溢出，从而导致未定义行为。

注意：C 语言中未定义行为的结果是不可预测的，可能会导致程序终止，也可能会继续执行。因此，编写代码时应避免出现未定义行为。

相关问题

Briefly describe the following diagrams: a.Class diagrams b.Use case diagrams: c.Objects diagrams d.Interaction diagrams

a. Class diagrams: Class diagrams are a type of structural diagram that represents the structure of a system by showing its classes, attributes, methods, and their relationships.

b. Use case diagrams: Use case diagrams are a type of behavioral diagram that represents the functionality of a system by showing the interactions between actors and use cases.

c. Object diagrams: Object diagrams are a type of structural diagram that represents a snapshot of a system at a particular point in time by showing objects and their relationships.

d. Interaction diagrams: Interaction diagrams are a type of behavioral diagram that represents the dynamic behavior of a system by showing the interactions between objects or actors. There are two types of interaction diagrams: sequence diagrams and communication diagrams. Sequence diagrams show the interactions between objects in a sequential order, while communication diagrams show the interactions between objects in a more concurrent way.

For a given PNP transistorExplain briefly what voltages need to be applied so that this transistor will work in the active (linear) region. Sketch a circuit showing the polarity of your power supplies.

To operate a PNP transistor in the active (linear) region, the following voltages need to be applied:

1. The base-emitter junction should be forward-biased, which means the voltage at the base should be more negative than the voltage at the emitter.

2. The collector-base junction should be reverse-biased, which means the voltage at the collector should be more positive than the voltage at the base.

A simple circuit to demonstrate this would be:

      +Vcc
        |
       / \
      /   \ R1
     /     \
     \     /
      \   /
       \ /
     |/ \| PNP
      |
      _
      |
      -
      |
      0V

In this circuit, the positive power supply is connected to the collector of the PNP transistor, and the negative power supply is connected to the emitter. The base is biased with a resistor R1 and a voltage source can be used to set the base voltage. The resistor R1 limits the current flowing into the base to protect the transistor from damage.

By applying the correct voltages to the base, collector, and emitter, the transistor will operate in the active (linear) region and can be used for amplification or switching purposes.