C语言可以用到的单词(国外英文资料).doc

C语言可以用到的单词(国外英文资料) You cant change people, but you can change yourself. You cant change the weather, but you can change your mood. You cant change the length of your life, but you can expand it. The first keyword: auto Used to declare automatic variables. You can explicitly declare variables as automatic variables. As long as the variable is not declared before all functions, the default is automatic, even if there is no auto keyword. And it only works in the function that declares it. And when it is done, its value is automatically restored to its original value. The automatic variable is used when it is used because it contains unknown values. Example: auto int name = 1; The second keyword: static Used to declare static variables. You can explicitly declare variables as static variables. Its also a local variable. It only works in the function that declares it. Its life cycle starts from the program and ends with the program. And even after its done, its value is still unrecovered. Even if you do not assign a value to a static variable, it will automatically initialize itself to 0. Third key word: extern Used to declare global variables. It also states that the variables before the main function are called global variables. It can be used anywhere in the program. Its always there during the program run. Global variables are also initialized to 0. The fourth keyword: register Used to declare a register variable. It is also a local variable, only valid for the function that declares it. It is stored in registers. Its much faster. Using it for variables that need to be used frequently will make the program run faster. Example: register int name = 1; The fifth keyword: int Used to declare the type of variable. Int for integers. Note that the scope is different in 16 and 32-bit systems. Two bytes in 16 bits. Four bytes in 32-bit. There is also an explicit declaration of unsigned or signed: unsigned int signed int. The difference between the symbol and the unsigned is