_Rupfb () -提供前次 I/O 作業的相關資訊

格式

#include <recio.h>

_RIOFB_T *_Rupfb(_RFILE *fp);

語言層次

ILE C 延伸

安全執行緒

是

不過，如果在執行緒之間傳遞檔案指標，則會在那些執行緒之間共用 I/O 回饋區域。

說明

_Rupfb() 函數會以前次 I/O 作業的相關資訊來更新與 fp 所指定檔案相關聯的回饋結構。即使在開啟檔案時指定 riofb = N ，也會更新 _RIOFB_T 結構。將不會更新 _RIOFB_T 結構的 num_bytes 欄位。如需 _RIOFB_T 結構的說明，請參閱 <recio.h> 。

_Rupfb() 函數適用於所有類型的檔案。

回覆值

_Rupfb() 函數會將指標傳回 fp指定的 _RIOFB_T 結構。如需錯誤碼設定，請參閱表 1 及表 1 。

範例

#include <stdio.h>
#include <recio.h>
#include <stdlib.h>
 
int main(void)
{
    _RFILE   *fp;
    _RIOFB_T *fb;
    /* Create a physical file                                        */
    system("CRTPF FILE(QTEMP/MY_FILE) RCDLEN(80)");
    /* Open the file for write                                       */
    if ( (fp = _Ropen("QTEMP/MY_FILE", "wr")) == NULL )
    {
        printf("open for write fails\n");
        exit(1);
    }
    /* Write some records into the file                              */
    _Rwrite(fp, "This is record 1", 16);
    _Rwrite(fp, "This is record 2", 16);
    _Rwrite(fp, "This is record 3", 16);
    _Rwrite(fp, "This is record 4", 16);
    _Rwrite(fp, "This is record 5", 16);
    _Rwrite(fp, "This is record 6", 16);
    _Rwrite(fp, "This is record 7", 16);
    _Rwrite(fp, "This is record 8", 16);
    _Rwrite(fp, "This is record 9", 16);
    /* Close the file                                                */
    _Rclose(fp);
    /* Open the file for read                                        */
    if ( (fp = _Ropen("QTEMP/MY_FILE", "rr, blkrcd = y")) == NULL )
    {
        printf("open for read fails\n");
        exit(2);
    }
    /* Read some records                                             */
    _Rreadn(fp, NULL, 80, __DFT);
    _Rreadn(fp, NULL, 80, __DFT);
    /* Call _Rupfb and print feed back information                   */
    fb = _Rupfb(fp);
    printf("record number -------------------------- %d\n",
           fb->rrn);
    printf("number of bytes read ------------------- %d\n",
           fb->num_bytes);
    printf("number of records remaining in block --- %hd\n",
           fb->blk_count);
    if ( fb->blk_filled_by == __READ_NEXT )
    {
        printf("block filled by ------------------------ __READ_NEXT\n");
    }
    else
    {
        printf("block filled by ------------------------ __READ_PREV\n");
    }
    /* Close the file                                                */
    _Rclose(fp);
}