What is dynamic memory allocation?

Dynamic memory allocation refers to the ability to allocate memory during the execution of a program, which allows for greater flexibility in managing memory. This is achieved using functions like malloc(), calloc(), and realloc() in the C programming language.

When a program is running, the exact amount of memory needed cannot always be foreseen, especially when handling data structures like arrays that can vary in size. Dynamic memory allocation enables the program to request and allocate memory as needed, adjusting for varying data sizes and allowing for efficient use of resources.

The use of functions like malloc() allows the programmer to specify the amount of memory to allocate, which is particularly useful in scenarios where the necessary memory size cannot be determined at compile time. This flexibility is a key feature of dynamic memory management, allowing programs to work with data structures that can grow or shrink during execution, enhancing performance and memory utilization.

In contrast, the other options describe memory management techniques that do not provide the same level of flexibility. For instance, allocating memory during compilation or statically at the start does not adapt to varying data requirements at runtime, and reallocating fixed memory, while somewhat related, does not encompass the overall process of dynamic memory allocation.