关键词: 变量状态转换模型,程序切片,软件错误

Abstract: Variables are used in a program in order to implement the function of a program.There are different operations about a variable in a program and the operation on a variable can change the state of a variable.According to the different usage of a variable,different states of a variable were analyzed.First,the safe and unsafe states of a normal variable and a pointer variable were defined in this paper.Then the rules about the change between different states were also defined.After that,the state transition model of variable was provided.By using the state transition model of variable and the theory of program slice,a variable’s unsafe state can be traced.

Key words: State transition model of variable,Program slice,Software error