strstr找不到子字符串，但缓冲区包含该值 [英] strstr cannot find substring but buffer contains the value

问题描述

我正在尝试使用STM32F407V6T6和CubeMx进行UART.

I was trying UART using STM32F407V6T6 and CubeMx.

我的UART工作正常.比较缓冲区时遇到的问题:我正在使用strstr()检查缓冲区是否包含有效的子字符串.

My UART is working fine. The problem I'm getting while comparing the buffer: I am using strstr() to check that my buffer contains valid substring or not.

这是代码:

uint8_t buff[10];

int main(void) {
    HAL_Init();
    SystemClock_Config();
    MX_GPIO_Init();
    MX_USART2_UART_Init();
    Green_Blink(100);
    Orange_Blink(100);
    Blue_Blink(100);
    Red_Blink(100);

    __HAL_UART_ENABLE_IT(&huart2, UART_IT_TC);
    __HAL_UART_ENABLE_IT(&huart2, UART_IT_RXNE);
    HAL_Delay(1000);

    while (1) {
        HAL_UART_Transmit_IT(&huart2, (uint8_t *)"AT\r\n", 5);
        Orange_Blink(100);
        HAL_Delay(1000);
        HAL_UART_Receive_IT(&huart2, buff, 10);
        buff[9] = '\0';
        if (buff[6] == 'O' && buff[7] == 'K') {
            Green_Blink(1000);    //Blinks
        }
        if (strstr((char*)buff, "OK")) {
            Red_Blink(1000);      //Doesn't blink
        }
        Clear_Buffer((char*)buff);
    }
}

这里我正在做的是我已连接我的GSM Module Sim800并发送了AT.调试我的代码后，我发现buff[6] = 'O'和buff[7] = 'K'.并且在检查我可以使LED闪烁的同时.

Here what I am doing is I have connect my GSM Module Sim800 and I send AT. After debugging my code I found that buff[6] = 'O' and buff[7] = 'K'. And while checking that I could blink the led.

        if (buff[6] == 'O' && buff[7] == 'K') {
            Green_Blink(1000);    //Blinks
        }

但是当我尝试使用功能strstr()时，它不会返回任何内容.

But when I try function strstr() It doesn't return anything.

        if (strstr((char*)buff, "OK")) {
            Red_Blink(1000);   //RED LED DOENS'T Blink
        }

起初我以为我的数组buff没有以\0结尾.所以我做到了

At first I thought my array buff is not ending with \0. So I did this

     buff[9] = '\0';

但是什么都没有改变.

关于为什么它不能与strstr()一起使用的任何建议.

Any suggestions why it's not working with strstr().

谢谢.

推荐答案

从您的观察和分析来看，buff确实在偏移量6包含OK，并且在偏移量9处为空终止.

From your observations and analysis, buff does contain OK at offset 6 and is null terminated at offset 9.

如果strstr在buff中找不到OK，则可能的解释是buff可能在偏移6之前包含另一个空终止符，并且OK在该空终止符之前不存在.

If strstr does not find OK in buff, a possible explanation is buff may contain another null terminator before offset 6 and OK is not present before this null terminator.

buff被初始化为所有位0，因此任何未更改的元素都是空终止符. HAL_UART_Receive_IT是否还可能将空字节存储到buff中?空字节有时在串行传输中用作填充.

buff is initialized to all bits 0, so any element that is not changed is a null terminator. Is it also possible that HAL_UART_Receive_IT store null bytes into buff? null bytes are sometimes used as padding in serial transmissions.

C库函数strstr也有可能在您的目标平台上不起作用.以前，我的嵌入式ST平台上的错误字符串功能及其工具集产生了无法解释的错误.

It is also possible that the C library function strstr does not work on your target platform. I once had an inexplicable streak of bugs from faulty string functions on embedded ST platforms with their toolset.

这篇关于strstr找不到子字符串，但缓冲区包含该值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！