ff_fgets()

[FreeRTOS-Plus-FAT 标准 API 引用]

ff_stdio.h

char *ff_fgets( char *pcBuffer, size_t xCount, FF_FILE *pxStream );

从文件中读取字符串的步骤为：将字节从 pxStream 读入 pcBuffer，直至读取了 (xCount - 1) 个字节，或直至换行符 ('n') 已读入 pcBuffer。

回车字符 ('r') 不以任何特殊方式处理，并且会复制到 pcBuffer 中。

复制到 pcBuffer 中的字符串在 ff_fgets() 返回之前为 NULL。

参数：

pcBuffer	指向缓冲区的指针，从文件读取的字符将被放置在该缓冲区中。缓冲区必须至少足够容纳 xCount 字节。
xCount	将从文件读取字节，直至接收到换行符，或已读取 (xCount - 1) 个字节。
pxStream	指向数据待读取的文件的指针。该指针与调用 ff_fopen() 返回的指针相同，最初用于打开文件。

返回：

如果成功，返回指向 pcBuffer 的指针。如果有读取错误则返回 NULL，并且任务的 errno 被设置为指示原因。任务可以使用 stdioGET_ERRNO() API 函数获取其 errno 值。

用法示例：



static void prvTest_ff_fgets_ff_printf( const char *pcMountPath )

{

FF_FILE *pxFile;

int iString;

const int iMaxStrings = 1000;

char pcReadString[ 20 ], pcExpectedString[ 20 ], *pcReturned;

const char *pcMaximumStringLength = "Test string 999n";



    /* Open a file for reading and writing. */

    pxFile = ff_fopen( "/nand/myfile.txt", "w+" );



    /* Use ff_fprintf() to write some strings to the file.  The strings are

    generated as "Test string nnnn", where nnn is the loop counter. */

    for( iString = 0; iString < iMaxStrings; iString++ )

    {

        /* Call ff_fprintf() to write the formatted string to the file.  Note

        the n character on the end of the string. */

        ff_fprintf( pxFile, "Test string %dn", iString );

    }



    /* Move back to the start of the file. */

    ff_rewind( pxFile );



    /* This time use the ff_fgets() string to read back each string at a time,

    then compare it against the expected string.  The strings were written with

    a newline character at their end, so ff_fgets() will read up to and

    including the newline. */

    for( iString = 0; iString < iMaxStrings; iString++ )

    {

        /* Read back the next string. */

        pcReturned = ff_fgets( pcReadString, sizeof( pcReadString ), pxFile );



        if( pcReturned != pcReadString )

        {

            /* Error! */

        }

        else

        {

            /* Generate the string that is expected to have been read back. */

            sprintf( pcExpectedString, "Test string %dn", iString );



            /* Compare the string that was expected to be returned against the

            string that was returned. */

            if( strcmp( pcExpectedString, pcReadString ) == 0 )

            {

                /* The strings matched, as expected. */

            }

            else

            {

                /* Error - the strings didn't match. */

            }

        }

    }



    ff_fclose( pxFile );

}



Example use of the ff_fgets() API function

出色的 RTOS & 嵌入式软件 下载 FreeRTOS 菜单

ff_fgets() [FreeRTOS-Plus-FAT 标准 API 引用]

出色的 RTOS & 嵌入式软件

下载 FreeRTOS
菜单

ff_fgets()

[FreeRTOS-Plus-FAT 标准 API 引用]