VFP封装结构类型示例（四） [结]
VFP封装结构类型，作为示例最后探讨一下数据结构与链表。VFP 的 DBF 也是应用数据结构与链表的产物，学VFP的对这方面了解一下可以加深对 DBF 的理解，也可以设计其他格式的数据文件。
相关文件
StructClass_demo.rar
(7.87 KB)
程序代码：
CLEAR
cDefPath = ADDBS(JUSTPATH(SYS(16)))
SET DEFAULT TO (cDefPath)
#INCLUDE apiFuns.h
SET PROCEDURE TO apiFuns.prg, StructClass.prg ADDITIVE
LoadApi()
ds = CREATEOBJECT("数据结构")
ds.create()
dt = CREATEOBJECT("数据表")
bufSize = ds.size
pBuffer = myMalloc(bufSize)
head = 0 && 头记录指针
last = 0 && 尾记录指针
filename = cDefPath + "test.dat"
load_data(filename)
add_data("张三", 1, 18, 170)
add_data("李四", 2, 22, 175)
list_data()
save_data(filename)
SET PROCEDURE TO
CLEAR ALL
RETURN
DEFINE CLASS 数据结构 as STRUCT_CLASS
PROCEDURE init
this.stInit("name", "C",10)
this.stInit("num1", "U",1)
this.stInit("num2", "I",2)
this.stInit("num3", "I",4)
ENDPROC
ENDDEFINE
DEFINE CLASS 数据表 as STRUCT_CLASS
PROCEDURE init(ds)
this.stInit("数据记录", "C",17)
this.stInit("next", "U",4)
ENDPROC
ENDDEFINE
FUNCTION add_data(name, num1, num2, num3)
LOCAL ptr
ptr = dt.create()
ds.setValue("name", name, ptr)
ds.setValue("num1", num1, ptr)
ds.setValue("num2", num2, ptr)
ds.setValue("num3", num3, ptr)
dt.setValue("next", 0, ptr)
IF last != 0
dt.setValue("next", ptr, last)
ENDIF
IF head == 0
head = ptr
ENDIF
last = ptr
RETURN last
ENDFUNC
FUNCTION load_data(filename)
IF !FILE(filename)
RETURN 0
ENDIF
LOCAL fp, ptr
fp = myFOpen(filename, "rb")
IF fp == 0
RETURN 0
ENDIF
head = 0
last = 0
IF apiFRead(pBuffer,bufSize,1,fp) == 1
head = dt.create()
apiMemcpy_s(head, bufSize, pBuffer, bufSize)
dt.setValue("next", 0, head)
last = head
ENDIF
DO WHILE apiFRead(pBuffer,bufSize,1,fp) == 1
ptr = dt.create()
apiMemcpy_s(ptr, bufSize, pBuffer, bufSize)
dt.setValue("next", 0, ptr)
dt.setValue("next", ptr, last)
last = ptr
ENDDO
apiFClose(fp)
RETURN head
ENDFUNC
FUNCTION save_data(filename)
LOCAL fp, ptr
fp = myFOpen(filename, "wb")
IF fp == 0
RETURN 0
ENDIF
ptr = head
DO WHILE ptr != 0
apiFWrite(ptr, bufSize, 1, fp)
ptr = dt.getValue("next", ptr)
ENDDO
apiFClose(fp)
RETURN 1
ENDFUNC
FUNCTION list_data()
LOCAL ptr
ptr = head
DO WHILE ptr != 0
? ds.getValue("name", ptr)
?? ds.getValue("num1", ptr)
?? ds.getValue("num2", ptr)
?? ds.getValue("num3", ptr)
ptr = dt.getValue("next", ptr)
ENDDO
ENDFUNC
