Data structures: stacks (implemented with arrays)

The following is the complete code:

/* * this file if an implementation of stack with array  list * file name: ArrayStack.c * author: John Woods *  date: 2015/5/10 * statement: anyone can use this file for  any purpose */#include  <stdio.h> #include  <stdlib.h> #include  <malloc.h > #define  INCREMENT 5#define MAX_LEN 20#define BOOL int#define TRUE  1#define false 0/* structure of the array stack */typedef struct  AStack {    int Length;    int MaxLength;     int * stackarray;} * astack;/* operation declaration */void stackinit (AStack * p_myAStack); Void stackdestroy (Astack * p_myastack); Void stackclear (astack mYastack); Void pop (Astack myastack); Void push (Astack myastack); Bool isexist (Astack myastack);/* menu declaration */void menu ();/* entrance :  main function */int main (void)  {    astack myastack =  NULL;    int choice;    char c;     while (TRUE)  {        menu ();         while (!scanf ("%d",  &choice))  while (' \ n '  !=  (C=getchar ())  & &AMP;&NBSP;EOF&NBSP;!=&NBSP;C);         switch (choice)  {             case 1:                 stackinit (&myAStack);            &nbsP;    break;            case  2:                 Stackclear (Myastack);                 break;            case 3:                 push (MyAStack);                 break;             case 4:                 pop (Myastack);                 break;             case 5:                 Stackdestroy (&myastack);                 break;            default:                 exit (EXIT_SUCCESS);                 break;         }    }    return 0;} /* menu implementation */void menu ()  {    printf ("\n\t*********** Menu***************\n ");     printf (" \t* 1.initial stack  2.clear  stack *\n ");     printf (" \t* 3.push           &nbsP;4.pop         *\n ");     printf (" \t* 5. destroy stack  6.exit        *\n ");     printf ("\t***************menu***************\n");     printf ("\tYour choice:   ");} /* operation implementation */void stackinit (Astack * p_myastack)  {     if (Isexist (*p_myastack))  {        printf ("This  stack is already exist! please destroy it first!\n ");         return;    }    *p_myastack =   (astack) malloc (sizeof (Struct astack));     if (Null == *p_myastack)  {        printf ("out memory! initial  Unsuccessfully!\n ");         return;    }     (*p_myAStack)- >StackArray =  (int *) malloc (sizeof (int)  * max_len);     if (NULL  ==  (*p_myastack)->stackarray)  {        printf ("Out  memory! initial unsuccessfully!\n ");         printf (" Destroy the stack now...\n ");         stackdestroy (p_ Myastack);        return;    }      (*p_myastack)->length = 0;     (*p_myastack)->maxlength =  max_len;    printf ("initial successfully!\n");} Void stackdestroy (Astack * p_myastack)  {    if (!isExist (*p_myAStack))  {        prinTF ("this stack is not exist! please initial it first!\n");         return;    }    free ((*p_myAStack) ->stackarray);     free (*p_myastack);    *p_myastack =  null;    printf ("destroy successfully!\n");} Void stackclear (Astack myastack)  {    if (!isexist (myAStack))  {         printf ("This stack is not exist! please  initial it first!\n ");        return;     }    myastack->length = 0;    printf ("Clear  successfully!\n ");} Void pop (Astack myastack)  {    int value;    char  c;    if (!isexist(Myastack))  {        printf ("this stack is not exist!  please initial it first!\n ");        return;     }    while (TRUE)  {         if (0 == myastack->length)  {             printf ("this stack has no element! pop unsuccessfully!\n");             return;         }        value = * (MyAStack->StackArray &NBSP;+&NBSP;MYASTACK-&GT;LENGTH&NBSP;-&NBSP;1);        myastack-> length--;        printf ("pop successfully! the popped  value is&Nbsp;%d\n ",  value);                         while (' \ n '  !=  (C=getchar ())  & &AMP;&NBSP;EOF&NBSP;!=&NBSP;C);         printf ("Go on?" ( y/n)           if (' Y '  !=  (C=getchar ())  &&   ' Y '  != c)  break;    }}void push (astack myastack)  {     int value;    char c;    if (!isExist (Myastack))  {        printf ("this stack is not exist!  please initial it first!\n ");        return;     }    while (TRUE)  {         if (myastack->lengtH >= myastack->maxlength)  {             if (null ==  (myastack =  (astack) realloc (myastack, sizeof (int)  *  INCREMENT))  {                 printf ("out of memory! push unsuccessfully!\n");                 return;             }             myastack->maxlength += increment;        }         printf ("Please input value:");         while (!scanf ("%d",  &value))  while (' \ n '  !=  (C=getchar ())  & &AMP;&NBSP;EOF&NBSP;!=&NBSP;C);         * (Myastack->stackarray + myastack->length)  = value;        myAStack->Length++;         printf ("push successfully! the pushed value is %d\ n ",  value);             while (' \ n '  !=   (C=getchar ())  && eof != c);         printf ("Go on?" ( y/n)           if (' Y '  !=  (C=getchar ())  &&   ' Y '  != c)  break;    }}bool isexist (astack myastack)  {     if (Null == myastack)  return false;    else  return true;}

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Data structures: stacks (implemented with arrays)