void PostOrder(BiTree T) { SqStack S; InitStack(&S); BiTNode *p = T; BiTNode *r = NULL; while (p || !IsEmpty(&S)) { if (p) // 走到最左边 { push(&S, *p); p = p->lchild; } else // 向右 { GetTop(S, *p); // 读栈顶结点（非出栈） if (p->rchild && p->rchild != r) // 若右子树存在，且未被访问过 p = p->rchild; // 转向右 else // 否则，弹出结点并访问 { pop(&S, p); // 将节点弹出 printf("%c ", p->data); // 访问该节点 r = p; // 记录最近访问过的结点 p = NULL; // 结点访问完后，重置p指针 } } } }

好的，根据您提供的程序，以下是一个完整的C语言程序：

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

#define MAXSIZE 100

typedef char ElemType;

typedef struct BiTNode {
    ElemType data;
    struct BiTNode *lchild, *rchild;
} BiTNode, *BiTree;

typedef struct {
    BiTNode data[MAXSIZE];
    int top;
} SqStack;

void InitStack(SqStack *S) {
    S->top = -1;
}

int IsEmpty(SqStack *S) {
    if (S->top == -1) {
        return 1;
    } else {
        return 0;
    }
}

int push(SqStack *S, BiTNode e) {
    if (S->top == MAXSIZE - 1) {
        return 0;
    }
    S->top++;
    S->data[S->top] = e;
    return 1;
}

int pop(SqStack *S, BiTNode *e) {
    if (S->top == -1) {
        return 0;
    }
    *e = S->data[S->top];
    S->top--;
    return 1;
}

int GetTop(SqStack S, BiTNode *e) {
    if (S.top == -1) {
        return 0;
    }
    *e = S.data[S.top];
    return 1;
}

void PostOrder(BiTree T) {
    SqStack S;
    InitStack(&S);
    BiTNode *p = T;
    BiTNode *r = NULL;
    while (p || !IsEmpty(&S)) {
        if (p) {
            push(&S, *p);
            p = p->lchild;
        } else {
            GetTop(S, p);
            if (p->rchild && p->rchild != r) {
                p = p->rchild;
            } else {
                pop(&S, p);
                printf("%c ", p->data);
                r = p;
                p = NULL;
            }
        }
    }
}

int main() {
    // 构造一棵二叉树
    BiTNode node1 = {'A', NULL, NULL};
    BiTNode node2 = {'B', NULL, NULL};
    BiTNode node3 = {'C', NULL, NULL};
    BiTNode node4 = {'D', NULL, NULL};
    BiTNode node5 = {'E', NULL, NULL};
    BiTNode node6 = {'F', NULL, NULL};
    BiTNode node7 = {'G', NULL, NULL};
    BiTNode node8 = {'H', NULL, NULL};
    BiTNode node9 = {'I', NULL, NULL};

    node1.lchild = &node2;
    node1.rchild = &node3;
    node2.lchild = &node4;
    node2.rchild = &node5;
    node3.lchild = &node6;
    node3.rchild = &node7;
    node5.rchild = &node8;
    node7.lchild = &node9;

    BiTree T = &node1;

    PostOrder(T); // 输出二叉树的后序遍历结果

    return 0;
}

注意，这里只是一个示例程序，您需要根据具体需求进行修改和调整。