Memory allocation

Dynamic memory allocation:

• Dynamic memory allocation means, a program can obtain its memory while it is running.
•  It allows us to allocate additional memory space or release unwanted space (i.e. previously allocated) at the time of program execution (runtime).
• The dynamic memory allocation is efficiently allowed to share the memory.
• It is very useful to modify the size of the previous allocated memory.

Static memory:

• So far, we have used static memory. Static memory means which reserve a certain amount of memory by default inside the program to use for variables and such.
• It means that once reserve this memory, no other the program can use it, even if we are not using it at the time.

Dynamic memory allocation function:

• Pointers support the dynamic memory allocation in ‘c’ language.
• The ‘C’ language provides four library functions known as ‘Memory Management Function’ which can be used for allocating and realising memory during execution.
• Any program, which uses these below functions, must be including the header file.

                                      #include<stdlib.h>

Example program:

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

void main()

{

char *p;//pointer variable

clrscr();

p=(char *) malloc(6);//allocate memory space to variable

strcpy(p,"MADRAS");

printf("\n Memory contains: %s\n",p);

p=(char *) realloc(p,7);//reallocation

strcpy(p,"CHENNAI");//string cpoy

printf("\n Memory now contains: %s\n",p);

free(p);// releasing memory

getch();

}

Output:

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