1.结构体的声明需放在函数的最前面

源代码：

	/*开启时钟*/RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);	//开启USART1的时钟RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);	//开启GPIOA的时钟/*GPIO初始化*/GPIO_InitTypeDef GPIO_InitStructure;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);					//将PA9引脚初始化为复用推挽输出GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);					//将PA10引脚初始化为上拉输入/*USART初始化*/USART_InitTypeDef USART_InitStructure;					//定义结构体变量USART_InitStructure.USART_BaudRate = 9600;				//波特率USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;	//硬件流控制，不需要USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;	//模式，发送模式和接收模式均选择USART_InitStructure.USART_Parity = USART_Parity_No;		//奇偶校验，不需要USART_InitStructure.USART_StopBits = USART_StopBits_1;	//停止位，选择1位USART_InitStructure.USART_WordLength = USART_WordLength_8b;		//字长，选择8位USART_Init(USART1, &USART_InitStructure);				//将结构体变量交给USART_Init，配置USART1/*中断输出配置*/USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);			//开启串口接收数据的中断/*NVIC中断分组*/NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);			//配置NVIC为分组2/*NVIC配置*/NVIC_InitTypeDef NVIC_InitStructure;					//定义结构体变量NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;		//选择配置NVIC的USART1线NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//指定NVIC线路使能NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;		//指定NVIC线路的抢占优先级为1NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;		//指定NVIC线路的响应优先级为1NVIC_Init(&NVIC_InitStructure);							//将结构体变量交给NVIC_Init，配置NVIC外设/*USART使能*/USART_Cmd(USART1, ENABLE);								//使能USART1，串口开始运行

会报错

这里错误信息提示我们，“声明不能出现在可执行语句之后”
那么修改为

	GPIO_InitTypeDef GPIO_InitStructure;USART_InitTypeDef USART_InitStructure;	//定义结构体变量	NVIC_InitTypeDef NVIC_InitStructure;	//定义结构体变量/*开启时钟*/RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);	//开启USART1的时钟RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);	//开启GPIOA的时钟/*GPIO初始化*/GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);					//将PA9引脚初始化为复用推挽输出GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);					//将PA10引脚初始化为上拉输入/*USART初始化*/USART_InitStructure.USART_BaudRate = 9600;				//波特率USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;	//硬件流控制，不需要USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;	//模式，发送模式和接收模式均选择USART_InitStructure.USART_Parity = USART_Parity_No;		//奇偶校验，不需要USART_InitStructure.USART_StopBits = USART_StopBits_1;	//停止位，选择1位USART_InitStructure.USART_WordLength = USART_WordLength_8b;		//字长，选择8位USART_Init(USART1, &USART_InitStructure);				//将结构体变量交给USART_Init，配置USART1/*中断输出配置*/USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);			//开启串口接收数据的中断/*NVIC中断分组*/NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);			//配置NVIC为分组2/*NVIC配置*/NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;		//选择配置NVIC的USART1线NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//指定NVIC线路使能NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;		//指定NVIC线路的抢占优先级为1NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;		//指定NVIC线路的响应优先级为1NVIC_Init(&NVIC_InitStructure);							//将结构体变量交给NVIC_Init，配置NVIC外设/*USART使能*/USART_Cmd(USART1, ENABLE);			

将结构体声明放在最前面，程序就不报错了。