diff --git a/_02.栈与队列/_b.共享栈.c b/_02.栈与队列/_b.共享栈.c
new file mode 100644
index 0000000..62f6cee
--- /dev/null
+++ b/_02.栈与队列/_b.共享栈.c
@@ -0,0 +1,151 @@
+/*
+ * @Author: Xu Bai
+ * @Date: 2019-06-30 20:54:59
+ * @LastEditors: Xu Bai
+ * @LastEditTime: 2019-06-30 21:25:05
+ */
+#include "stdio.h"
+#include "stdlib.h"
+#include "io.h"
+
+#define MAXSIZE 20
+#define TRUE 1
+#define FALSE 0
+#define OK 1
+#define ERROR 0
+
+typedef int Status;
+typedef int ElemType;
+
+typedef struct
+{
+    ElemType data[MAXSIZE];
+    int top1;
+    int top2;
+} SqDoubleStack;
+
+Status visit(ElemType e)
+{
+    printf("%d ", e);
+    return OK;
+}
+
+Status InitStack(SqDoubleStack *S)
+{
+    S->top1 = -1;
+    S->top2 = MAXSIZE;
+    return OK;
+}
+
+Status ClearStack(SqDoubleStack *S)
+{
+    S->top1 = -1;
+    S->top2 = MAXSIZE;
+    return OK;
+}
+
+Status StackEmpty(SqDoubleStack S)
+{
+    if (S.top1 == -1 && S.top2 == MAXSIZE)
+    {
+        return TRUE;
+    }
+    return FALSE;
+}
+
+int StackLength(SqDoubleStack S)
+{
+    return (S.top1 + 1) + (MAXSIZE - S.top2);
+}
+
+Status Push(SqDoubleStack *S, ElemType e, int stackNumber)
+{
+    if (S->top1 + 1 == S->top2)
+    {
+        printf("Stack overflow");
+        return ERROR;
+    }
+    if (stackNumber == 1)
+    {
+        S->data[++S->top1] = e;
+    }
+    else if (stackNumber == 2)
+    {
+        S->data[--S->top2] = e;
+    }
+    else
+    {
+        printf("stackNumber = 1 or 2");
+        return ERROR;
+    }
+    return OK;
+}
+
+Status Pop(SqDoubleStack *S, ElemType *e, int stackNumber)
+{
+    if (stackNumber == 1)
+    {
+        if (S->top1 == -1)
+        {
+            return ERROR;
+        }
+        *e = S->data[S->top1--];
+    }
+    else if (stackNumber == 2)
+    {
+        if (S->top2 == MAXSIZE)
+        {
+            return ERROR;
+        }
+        *e = S->data[S->top2++];
+    }
+    else
+    {
+        return ERROR;
+    }
+
+    return OK;
+}
+
+Status StackTraverse(SqDoubleStack S)
+{
+    int i = 0;
+    while (i <= S.top1)
+    {
+        visit(S.data[i++]);
+    }
+    i = S.top2;
+    while (i < MAXSIZE)
+    {
+        visit(S.data[i++]);
+    }
+    printf("\n");
+    return OK;
+}
+
+int main()
+{
+    int j;
+    ElemType e;
+    SqDoubleStack S;
+    InitStack(&S);
+    for (j = 0; j <= 5; j++)
+    {
+        Push(&S, j, 1);
+    }
+    for (j = MAXSIZE; j >= MAXSIZE - 2; j--)
+    {
+        Push(&S, j, 2);
+    }
+    printf("Traverse: \n");
+    StackTraverse(S);
+    printf("pop 1 &2 \n");
+    Pop(&S, &e, 1);
+    Pop(&S, &e, 2);
+    StackTraverse(S);
+    ClearStack(&S);
+    printf("Clear!\n");
+    StackTraverse(S);
+    getchar();
+    return OK;
+}
\ No newline at end of file
diff --git a/a.out b/a.out
index 96d5ea3..4dee120 100644
Binary files a/a.out and b/a.out differ