数据结构，栈，顺序表示

进栈
void push_seq(PSeqstack pastack,DataType x)
{
    if(pastack->t >= MAXNUM-1)printf("Overflow! \n");
    else
           { pastack->t=pastack->t+1;
             pastack->s [ pastack->t ]=x;
           }
}



出栈
void pop_seq(PSeqStack pastack)
{
if(pastack->t==-1)printf("underflow!\n");
else pastack->t = pastack->t - 1;
}


取栈顶元素
DataType top_seq(PseqStack pastack)
{
if(pastack->t==-1)printf("It is empty!\n");
else return(pastack->s[ pastack->t ]);
}