使用printf进行浮点打印时，程序跑飞

发布于 2023-04-26 11:43:36 浏览：742 订阅该版

[tocm]

# 环境：
硬件环境：AT32F403A
IDE:keil
编译器：AC6
系统：rt thread nano

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230426/f3b17c0c17434f7ba680e9e69938a0e9.png)

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230426/e096158ae5f2c0c00dc4136bb126b6ea.png)
# 问题描述问题描述：
使用printf进行浮点打印时，程序跑飞
## 程序如下程序如下：
```c
int main(void)
{
    Usart1Init(921600);
    SysTickInit(5);
    while (1)
    {
        printf("delay %f\r\n",0.02);
//        Delay_ms(1000);
        rt_thread_mdelay(1000);
    }
}
```

## 串口输出串口输出：

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230426/793795a6059b8cee73e1c034c42f669f.png)
进行调试，发现程序跑飞：

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230426/c15fa0c4dbe565219ca9d8558f9fbe34.png.webp)
## 尝试解决尝试解决：
1.printf期间禁止调度，无法解决

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230426/3fcaca36b859594efb8b5a65eb4a2d4c.png.webp)
2.mian线程一直占用cpu，不进行线程切换，正常输出

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230426/55cea698c80cceddbd74a07905154aee.png.webp)

3.不进行浮点输出且进行线程切换，正常

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230426/f2c58bd2a0501039d4c44f94b4d778e4.png.webp)

# 问题点猜测
使用printf打印浮点后，发生线程切换后会跑飞
**但这是为什么呢？**