"Play through the corners of embedded C" When you need the loop body to execute at least once, choose do

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When you need the loop body to be executed at least once, choose do-----《C and Pointers》

1. Concept

       Usually, we often use the while statement to express our idea of ​​" judging first and then looping ". In addition, the while statement has a brother called do statement, or do-while. His distinctive feature is " looping first and then judging ", which will be executed at least once loop body.
The syntax of do is:

do{
    
    
      statement   //为循环体
}while(expresssion);  //expresssion测试表达式，其值为1或0

2. The execution process of the do statement

When to use a do-while statement instead of a while() statement?
When you need the loop body to execute at least once, choose do

3. Please remember to bring it;

       I want to emphasize that many people who are not in the habit of using do-while statements often make a low-level mistake when they have to use do-while statements to deal with problems -- forgetting an important point No. while(expression);

This do-while statement is often used in the process of MCU USART debugging and sending data

void usart_SendString(u8 *str)
{
    
    
	u8 index=0;
	do
	{
    
    
		USART_SendData(USART2,str[index]);				//发送数据
		while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
		//若数据没有发送完成，则会死在while语句里面！
		index++;
	}while(str[index] != 0);						//检查字符串结束标志
}

	while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
	//其他人还偏爱于另一种写法：
	while(!USART_GetFlagStatus(USART2,USART_FLAG_TXE));