Take a 32-bit unsigned integer variable as an example, and its maximum value is 4294967295 (2 32-1). When the variable value reaches the maximum value of 4294967295 and then increases 1, the variable value will become 0, that is, overflow has occurred.
Similarly, other data types have similar overflow phenomena. For example, for a signed integer variable, if it increases itself after reaching the maximum value, it will change from the maximum value to the minimum value, that is, overflow.
It should be noted that overflow may lead to unexpected results in program running, so when writing programs, we should pay attention to the value range of variables and deal with overflow reasonably.
Extended content:
Overflow occurs not only in self-increasing operations, but also in other mathematical operations, such as addition, subtraction and multiplication. Programmers need to judge and deal with possible overflow when processing data to avoid overflow leading to wrong results.
In some special application scenarios, overflow may be used to realize some functions. For example, in the implementation of the loop counter, when the counter reaches the maximum value and overflows back to 0, the function of loop counting can be realized. However, in general, overflow needs to be avoided, because it may lead to unpredictable behavior of the program.
In embedded systems such as STM32, overflow handling mechanisms are usually provided, such as using appropriate data types, checking overflow or using overflow safe operation libraries to avoid overflow problems.