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The Pascal programming language provides several functions for memory allocation and management. Refer to the following article by Mytour to learn about memory management in Pascal.
Dynamic Memory Allocation in Pascal
When working with programs, knowing the size of an array allows for easy definition. For instance, to store the name of a person, you can allocate up to 100 characters as shown below:
var
name: array[1..100] of char;
Consider the example below; suppose you do not have an idea about the length of a text segment you need to store, such as a detailed description of a topic. In this example, you need to define a pointer to an undefined string, requiring memory allocation.
Pascal provides the new procedure to create pointer variables.
Once the above code is compiled and executed, it will yield the following outcome:
Name = Zara Ali
Description: Zara Ali, a student at DPS, is in the 10th grade.
Next, if you need to define a pointer with a specific number of bytes, you use the getmem function or getmem routine, as shown below:
In the example above, a pointer to a string is declared. The string has a maximum value of 255 bytes. If you don't need much memory or need more memory, the getmem subroutine allows you to do this. Continuing from the example above, if you use getmem:
Once the above code is compiled and executed, it will yield the following outcome:
Name = Zara Ali
Description: Zara Ali, a student at DPS, is in the 10th grade
Thus, you have full control and can adjust memory allocation. Unlike arrays, once defined, you cannot change the memory size anymore.
Changing Size and Releasing Memory
When a program terminates, the operating system will automatically release the memory allocated by the program. However, if it's not needed, you can free that memory.
Pascal provides the dispose procedure to release dynamically allocated memory created by the new procedure. If memory allocation is done using the getmem subroutine, you will need to use the freemem subroutine to release memory.
The syntax of the freemem subroutine is as follows:
Additionally, you can increase or decrease the size of the allocated memory block by calling the ReAllocMem function. The syntax of checking a program using the ReAllocMem and freemem subroutines is as follows:
The example below illustrates how to use the ReAllocMem and freemem subroutines:
When the above code is compiled and executed, it will return the following result:
Name = Zara Ali
Description: Zara Ali, a student at DPS, is currently in the 10th grade
Memory Management Functions in Pascal
The article above by Mytour has just provided you with some information about memory management in Pascal as well as memory management functions in Pascal. Additionally, to learn about operators in Pascal, loop statements in Pascal, ... readers can refer to some articles already available on Mytour.
