Malloc(),Calloc(), Realloc(), Free(), Perror(), Rand(),Delay of C Function

Program for malloc() function in C

#include 

#include

#include 

#include 

int main()

{

     char *mem_allocation;

     mem_allocation = malloc( 20 * sizeof(char) );

     if( mem_allocation== NULL )

     {

        printf("Couldn't able to allocate requested memory\n");

     }

     else

     {

        strcpy( mem_allocation,"fresh2refresh");

     }

     printf("Dynamically allocated memory content : " \

            "%s\n", mem_allocation );

     free(mem_allocation);

}

Output

Dynamically allocated memory content: fresh2refresh

Program for calloc () function in C

#include 

#include

#include 

#include 

int main()

{

     char *mem_allocation;

     mem_allocation = calloc( 20, sizeof(char) );

     if( mem_allocation== NULL )

     {

        printf("Couldn't able to allocate requested memory\n");

     }

     else

     {

         strcpy( mem_allocation,"fresh2refresh");

     }

         printf("Dynamically allocated memory content   : " \

                "%s\n", mem_allocation );

         free(mem_allocation);

}

Output

Dynamically allocated memory content : fresh2refresh

Program for realloc() and free() functions in C

#include 

#include

#include 

#include 

int main()

{

    char *mem_allocation;

    mem_allocation = malloc( 20 * sizeof(char) );

    if( mem_allocation == NULL )

    {

        printf("Couldn't able to allocate requested memory\n");

    }

    else

    {

       strcpy( mem_allocation,"fresh2refresh");

    }

    printf("Dynamically allocated memory content  : " \

           "%s\n", mem_allocation );

    mem_allocation=realloc(mem_allocation,100*sizeof(char));

    if( mem_allocation == NULL )

    {

        printf("Couldn't able to allocate requested memory\n");

    }

    else

    {

        strcpy( mem_allocation,"space is extended upto " \

                               "100 characters");

    }

    printf("Resized memory : %s\n", mem_allocation );

    free(mem_allocation);

}

Output

Dynamically allocated memory content: fresh2refresh
Resized memory: space is extended upto 100 characters

Program for perror() function in C

             #include 

#include 

#include 

int main()

{

    FILE *fp;

    char filename[40] = "test.txt";

    fp = f open(filename, "r");

    if(fp == NULL)

    {

        perror("File not found");

        printf("errno : %d.\n", errno);

        return 1;

    }

    printf("File is found and opened for reading");

    fclose(fp);

    return 0;

}

Output

errno: 22.
File not found: No such file or directory

Program for rand () function in C

#include

#include

#include

int main ()

{

   printf ("1st random number :  %d\n", rand() % 100);

   printf ("2nd random number : %d\n", rand() % 100);

   printf ("3rd  random number: %d\n", rand());

   return 0;

}

Output

1st random number : 83
2nd random number : 86
3rd random number: 16816927

Program for delay() function in C

#include

#include

int main ()

{

   printf("Suspends the execution of the program " \"for particular time");

   delay(5000);        

   return 0;

}

Output

Suspends the execution of the program for particular time