In C programming, you will allocate memory dynamically by using the functions defined in the header files.

These functions are found in <stdlib.h> header file.

While programming, if you know the size of an array, then it is easy and you can define it as an array. 

char name[100];

In those situation where you have no idea about the length of the text you need to store then these functions will be handy.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {

   char name[100];
   char *description;

   strcpy(name, "Zara Ali");

   /* allocate memory dynamically */
   description = malloc( 200 * sizeof(char) );
	
   if( description == NULL ) {
      fprintf(stderr, "Error - unable to allocate required memory\n");
   }
   else {
      strcpy( description, "Zara ali a DPS student in class 10th");
   }
   
   printf("Name = %s\n", name );
   printf("Description: %s\n", description );
}

Same program with the different function can be used

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {

   char name[100];
   char *description;

   strcpy(name, "Zara Ali");

   /* allocate memory dynamically */
   description = malloc( 30 * sizeof(char) );
	
   if( description == NULL ) {
      fprintf(stderr, "Error - unable to allocate required memory\n");
   }
   else {
      strcpy( description, "Zara ali a DPS student.");
   }
	
   /* suppose you want to store bigger description */
   description = realloc( description, 100 * sizeof(char) );
	
   if( description == NULL ) {
      fprintf(stderr, "Error - unable to allocate required memory\n");
   }
   else {
      strcat( description, "She is in class 10th");
   }
   
   printf("Name = %s\n", name );
   printf("Description: %s\n", description );

   /* release memory using free() function */
   free(description);
}