Program: 141

Write a C program to show the storage, default initial value, scope and life of register storage class variables.

Variable Storage Class tells us:

1. Storage (location)
2. Default Initial Value of the variable
3. Scope of the variable
4. Life of the variable

1. Storage: Where the variable would be stored.

2. Default Initial Value: What will be the initial value of the variable, if initial value is not specifically assigned. (i.e. the default initial value)

3. Scope: What is the scope of the variable: i.e. in which functions the value of the variable would be available.

4. Life: What is the life of the variable: i.e. how long would the variable exist.

Register Storage Class:

Same as Automatic Storage Class but uses registers instead of memory.

Storage : CPU Registers
Default Initial Values : A garbage Value (unpredictable value)
Scope : Local to the block remains within the block in which the variable defined.
Life : Till the control remains within the block in which the variable is defined.

Note: We can’t say for sure that the value of register class variables would be stored in a CPU register, because the number of CPU registers are limited and they may busy doing some other task.

For example: if the microprocessor has 16-bit registers then they cannot hold a float value or a double value, which require 4 and 8 bytes respectively.

float (4 bytes)

=> 4 x 8

=> 32 bits

double (8 bytes)

=> 8 x 8

=> 64 bits

Output:

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