完成了表达式计算小程序

Chapter11/ds/line/compute/sqstack.c

@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "sqstack.h"
+
+sqstack *st_create(void)
+{
+    sqstack *st;
+
+    st = malloc(sizeof(*st));
+    if (NULL == st)
+        return NULL;
+
+    st->top = -1;
+
+    return st;
+}
+
+int st_isempty(sqstack *st)
+{
+    return (-1 == st->top);
+}
+
+int st_push(sqstack *st, datatype *data)
+{
+    if (MAXSIZE - 1 == st->top)
+        return -1;
+
+    st->data[++st->top] = *data;
+
+    return 0;
+}
+
+/* 取出栈顶元素 */
+int st_pop(sqstack *st, datatype *data)
+{
+    if (st_isempty(st))
+        return -1;
+
+    *data = st->data[st->top--];
+
+    return 0;
+}
+
+
+/* 查看栈顶元素 */
+int st_top(sqstack *st, datatype *data)
+{
+    if (st_isempty(st))
+        return -1;
+
+    *data = st->data[st->top];
+
+    return 0;
+}
+
+void st_travel(sqstack *st)
+{
+    if (st_isempty(st))
+        return;
+
+    int i;
+
+    for (i = 0; i <= st->top; i++)
+        printf("%d ", st->data[i]);
+    printf("\n");
+}
+
+void st_destroy(sqstack *st)
+{
+    free(st);
+}