Example program on Dynamic memory allocation in C language

Problem

Find out the maximum and minimum from an array using dynamic memory allocation in C.

Solution

The Dynamic memory allocation enables the C programmers to allocate memory at runtime.

The different functions that we used to allocate memory dynamically at run time are −

• The malloc () − allocates a block of memory in bytes at runtime.

• The calloc () − allocates continuous blocks of memory at runtime.

• The realloc () − used to reduce (or) extend the allocated memory.

• The free () − deallocates previously allocated memory space.

Finding maximum and minimum number in an array using dynamic memory allocation

The logic for finding maximum element in an array −

First allocate memory to the array

p=(int*)malloc(n*sizeof(int)); //dynamic memory allocation
for(i=0;i<n;i++){
   scanf("%d",p+i);
   if(*(p+i)>max) //finding max element
      max=*(p+i);
}

The logic for finding minimum element in an array −

for(i=0;i<n;i++){
   scanf("%d",p+i);
   if(*(p+i)<min) //finding min element
      min=*(p+i);
}

Example

 Live Demo

#include<stdio.h>
int main(){
   int *p,n,i,max=-32768,min=32767;
   printf("
 enter size:");
   scanf("%d",&n);
   p=(int*)malloc(n*sizeof(int)); //dynamic memory allocation
   printf("
 enter elements:");
   for(i=0;i<n;i++){
      scanf("%d",p+i);
      if(*(p+i)>max) //finding max element
         max=*(p+i);
      if(*(p+i)<min) //finding min element
         min=*(p+i);
   }
   printf("
 maximum=%d
 minimum=%d",max,min);
   free(p);
}

Output

enter size:
enter elements:
maximum=-32768
minimum=32767