of storage classes with varying features, believing that the programmer is in a best position to decide which one of these storage classes is to be used when. We can make a few ground rules for usage of different storage classes in different programming situations with a view to:
(a) economise the memory space consumed by the variables
(b) improve the speed of execution of the program
The rules are as under
Use static storage class only if you want the value of a variable to persist between different function calls.
− Use register storage class for only those variables that are being used very often in a program. Reason is, there are very few CPU registers at our disposal and many of them might be busy doing something else. Make careful utilization of the scarce resources. A typical application of register storage class is loop counters, which get used a number of times in a program.
− Use extern storage class for only those variables that are being used by almost all the functions in the program. This would avoid unnecessary passing of these variables as arguments when making a function call. Declaring all the variables as extern would amount to a lot of wastage of memory space because these variables would remain active throughout the life of the program.
− If you don’t have any of the express needs mentioned above, then use the auto storage class. In fact most of the times we end up using the auto variables, because often it so happens that once we have used the variables in a function we don’t mind loosing them.
− Use register storage class for only those variables that are being used very often in a program. Reason is, there are very few CPU registers at our disposal and many of them might be busy doing something else. Make careful utilization of the scarce resources. A typical application of register storage class is loop counters, which get used a number of times in a program.
− Use extern storage class for only those variables that are being used by almost all the functions in the program. This would avoid unnecessary passing of these variables as arguments when making a function call. Declaring all the variables as extern would amount to a lot of wastage of memory space because these variables would remain active throughout the life of the program.
− If you don’t have any of the express needs mentioned above, then use the auto storage class. In fact most of the times we end up using the auto variables, because often it so happens that once we have used the variables in a function we don’t mind loosing them.
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