栈实现

栈：限定仅在表尾进行插入或删除操作的线性表。
特点：先进后出(last in first out)LIFO

实现：

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

#define STACK_INIT_SIZE 100
#define STACKINCREMENT 10

typedef struct SqStack{
	char *base;
	char *top;
	int stacksize;
}SqStack;

int InitStack(SqStack &S);
int DestroyStack(SqStack &S);
int ClearStack(SqStack &S);
int StackEmpty(SqStack &S);
int StackLength(SqStack S);
int GetTop (SqStack &S,char &e);
int Push(SqStack &S,char &e);
int Pop(SqStack &S,char &e);
int StackTraverse(SqStack S);

int InitStack(SqStack &S){
	S.base = (char *) malloc (STACK_INIT_SIZE * sizeof(char));
	if(!S.base)
		exit(-1);
	S.top = S.base;
	S.stacksize = STACK_INIT_SIZE;
	return 1;
}

int GetTop(SqStack &S,char &e){
	if(S.top == S.base)
		return -1;
	e = *(S.top -1);
	return 1;
}

int push(SqStack &S,char &e){
	if(S.top - S.base >= S.stacksize){
		S.base = (char *) realloc(S.base,(S.stacksize + STACKINCREMENT)*sizeof(char));
		if(!S.base)
			exit(-1);
		S.top = S.base + S.stacksize;
		S.stacksize += STACKINCREMENT;
	}
	*S.top++ = e;
	return 1;
}
int Pop(SqStack &S,char &e){
	if(S.top == S.base)
		return -1;
	e = *--S.top;
	return 1;

}
int StackLength(SqStack S){
	return S.top - S.base;
}

int StackTraverse(SqStack S){
	char ch;
	for(int i = 0;i < StackLength(S);i++){
		ch = *(S.top - 1 - i);
		printf("%c ",ch);
	}
	return 1;
}

int StackEmpty(SqStack &S){
	if(S.top == S.base){
		return 1;
	}
	else 
		return 0;
}

int ClearStack(SqStack &S){
	 S.top = S.base; 
}

int DestroyStack(SqStack &S){
	free(S.base);
	S.base = NULL;
	S.top = NULL;
	S.stacksize = 0;
	return 1;
}

int main(){
	int n;
	char ch;
	int i;
	SqStack S;
	InitStack(S);
	char a[5]={'a','b','c','d','e'};
	for ( i = 0; i < 5; ++i)
	{
		push(S,a[i]);

	}

	StackTraverse(S);

	printf("\n");
	printf("%d",StackLength(S));
	printf("\n");

	/*清空栈*/
	while( !StackEmpty(S) ){
		Pop(S,ch);
		printf("%c ",ch);
	}

	return 0;
}