1, the broad concept of "constant" is:' invariant quantity' (for example, the quantity that will not be modified by the program when the computer program is running; A quantity in a mathematical function, such as the radius and diameter of each specific circle; Near-surface gravity acceleration in physics; The value of the speed of light in vacuum; In other words, constant is not a concept specially introduced for hardware, software and programming languages, although it serves hardware, software and programming languages in computer technology. Constants can be divided into different types, such as: 25 and 0 are integer constants, 6.8 is a real constant, and' a' and' b' are character constants. Constants can usually be judged from their literal forms. This constant is called literal constant or direct constant.

2. When discussing the relationship between the function value and the independent variable, there are often one or more constants in the function. People focus on the laws of these changes, and it is often easy to find the correct reflection of the development laws of things in their brains.

3. The popular metaphor of "invariability"-"Like a mountain that is not easy to change" (Of course, the acceleration of gravity on the earth will change with the ebb and flow of the sea; The constant used by people is a quantity that will not change for a long time. The speed of light in vacuum is constant.