原帖地址：http://www.amobbs.com/thread-5537678-1-1.html
在fatfs文件系统下，实现SD卡的读取追加内容，实现方法是：读取文件、偏移指针、填写内容。追加内容时需要利用f_sleek函数将指针移到文本尾 部，再写问容，具体实现main函数的功能是两个按键来控制添加不同的内容，按键1按下时添加 BYTE sample_buffer[] = "2710,2712,2711,2715,1234,2134,4567,7890 \r\n";按键2按下时添加 BYTE sample_buffer1[] = "1,2,3,4,5,6,7,8,9,0 \r\n";
printf 调试用，
问题是：保存到txt文件中的数据不规则，应该是每一行数据都是靠左边对齐才对，实际是如附件图片所示。

---

程序：

while (1)
    {   
        if( Key_Scan(GPIOE,GPIO_Pin_5) == KEY_ON) //按键1按下时添加 sample_buffer中内容
        {
                printf( "\r\n KEY1 PE5    \n" ); //串口输出调试信息
               
                res = f_open(&fdst,"0:/Demo.TXT", FA_WRITE); //打开文本，while之前已经        f_mount(0,&fs);

if( res == FR_OK)
            {
                printf( "\r\n SD has opened    \n" );
               
                    res = f_lseek(&fdst, f_size(&fdst));   
                res = f_write(&fdst, sample_buffer, sizeof(sample_buffer), &bw);
                    f_close(&fdst);
                printf( "\r\n sample_buffer \n" );
            }
        }
            if( Key_Scan(GPIOE,GPIO_Pin_6) == KEY_ON) //按键2按下时添加 sample_buffer1中内容
        {
                printf( "\r\n KEY2 PE6    \n" );
                  
                res = f_open(&fdst,"0:/Demo.TXT", FA_WRITE);

if( res == FR_OK)
            {
                printf( "\r\n SD has opened    \n" );
               
                    res = f_lseek(&fdst, f_size(&fdst));   
                res = f_write(&fdst, sample_buffer1, sizeof(sample_buffer), &bw);
                    f_close(&fdst);
                printf( "\r\n sample_buffer1 \n" );
            }
        }        
    }

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试验结果：txt文本内容
实际显示内容对齐方式是：

---

感谢您选用 野火STM32开发板 ！^_^
1,2,3,4,5,6,7,8,9,0
                            1,2,3,4,5,6,7,8,9,0
                            1,2,3,4,5,6,7,8,9,0
                            1,2,3,4,5,6,7,8,9,0
                            1,2,3,4,5,6,7,8,9,0
                            2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
1,2,3,4,5,6,7,8,9,0
                            1,2,3,4,5,6,7,8,9,0
                            1,2,3,4,5,6,7,8,9,0

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理论或是理想中的显示内容对齐方式是：

---

感谢您选用 野火STM32开发板 ！^_^
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
2710,2712,2711,2715,1234,2134,4567,7890
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0
1,2,3,4,5,6,7,8,9,0