stack.cpp

一个简单的编译器,接收表达式,并输出后缀表达式或者编译过程,可以计算的输出计算结果

#include "global.h"

Status InitStack(SqStack *S){/*构造一个运算数的空栈S*/
	S->base=(SElemType *)malloc(STACK_INIT_SIZE*sizeof(SElemType));
	if(!S->base) return(OVERFLOW) ;//存储分配失败
	S->top=S->base;
	S->stacksize=STACK_INIT_SIZE;
	return OK;
}

Status Push(SqStack *S,SElemType e){//插入e为新的运算数栈的栈顶元素
	if(S->top-S->base >= S->stacksize){//栈满,追加存储空间
		S->base=(SElemType *)realloc(S->base,(S->stacksize+STACKINCREMENT)*sizeof(SElemType));
		if(!S->base) return (OVERFLOW);//存储分配失败
		S->top=S->base+S->stacksize;
		S->stacksize += STACKINCREMENT;
	}
	*S->top++=e;
	return OK;
}
Status Pop(SqStack *S){//若运算数栈不为空,则删除S的栈顶元素,并用e返回其值
	if(S->top==S->base) return ERROR;
	return *--S->top;
}

Status DestroyStack(SqStack *S){//销毁运算数栈S
	free(S->base);
	return OK;
}