Tuesday, 12 February 2013

C Programming: Advantages and Drawbacks of Pointers

Pointers are more efficient in handling arrays and data tables. They can be used to return multiple values from a function via function arguments. Pointers permit references to functions and thereby facilitating passing of functions as arguments to other functions. The use of po0inter arrays to character strings results in saving of data storage space in memory. pointers allow C to support dynamic memory management. Pointers provide an efficient tool for manipulating dynamic data structures such as structures, linked lists, queues, stacks and trees. Pointers reduce length and complexity of programs. They increases the execution speed and thus reduce the program execution time.
Pointers have tremendous power but the power can swing both sides good and evil. Pointer if used incorrectly leads to very difficult to unearth bugs which will most probably make you go wild. Pointers are itself are not any trouble but the value they are storing can be. If it contains a incorrect value it can lead to disasters of massive magnitude when used.
When you use this incorrect pointer to read a memory location, you may be reading a incorrect garbage value which if unluckily accepted by your program as assumed correct value nothing can help you. Consider a scenario in banking in which any customers real account value is switched with this garbage value, he can become a millionaire or beggar in a second, or think that in a rocket launching software you use this incorrect value as launching angle and crashing the billion dollar masterpiece. These scenarios are just my imagination running wild but you cannot ignore the fact that they are possibility.
Now when you use this incorrect pointer to write a memory location you may be writing a unknown memory location. If you have a large memory in the system maybe you are using a unassigned memory but if that memory by any luck is a memory used by O.S. or Hardware and you are modifying it you maybe corrupting your Operating System software or damaging your hardware and their drivers. Also it is a possibility that you maybe using a memory location already in use by your software storing some essential data and you are unknowingly modifying it. You maybe writing over your own code and data.
Such bugs and errors created by the pointers may not show up immediately but come up later and it is at that time difficult to predict that it was the pointer to blamed.
Due to these drawbacks of pointers, Programming language like JAVA, C# cannot allow pointer operation.

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