Table of Content

Malloc Function : Dynamic memory allocation

Syntax :

ptr = (data_type *)malloc(No_of_elements*sizeof(data_type));

Steps to Understand :
1 . (data_type *):

• Type conversion or typecasting refers to changing an entity of one data type into another.
• Example : if we assign the integer 4 to floating variable then internally it is assigned as 4.00
• Similarly , Address of Block of memory is casted to address of Pointer .

2 . No_of_elements :

• No_of_elements is nothing but the “No of elements Created at run time”.
• i.e Suppose we want to allocate space for 10 integer variable then No_of_elements = 10

3 . Sizeof(data_type)

• Note Carefully : Sizeof is not function , it is Operator
• Sizeof operator calculates the memory required for variable,data type etc
• In malloc size of data_type is written .Data types specified in the first step must match with data type in this step.

Note : Example

ptr = (int *) malloc (10 * sizeof(int));

Malloc :

• Header File : stdlib.h
• Allocate 20 bytes of memory
• Sizeof Returns the Size of Parameter specified
• 10 means allocate space at run time for 10 elements
• (int *) means Typecasting i.e Address of Block of memory is casted to address of Pointer
• On Success : 20 bytes will be allocated
• On Fail : Returns NULL
• Memory Address is assigned to Pointer ptr
• Clears allocated memory to garbage value