c - C中的rs232字符串比较

Question

我正在尝试编写一个程序，它可以从 RS232 端口读取命令并将它们用于下一步操作。

我正在使用字符串比较命令将所需的“操作”字符串与 RS232 字符串进行比较。某处的字符串转换出了问题。我使用了一个 putstr 命令来查看我的微 Controller 从我的电脑上得到了什么，但它不能正常工作。它返回我的字符串的最后两个字符，中间有一个点或一个“d”。 (我完全不知道点​​/d 来自哪里..)

所以这是我的主要代码:

int length;
char *str[20];
while(1)
{
    delayms(1000);
    length = 5; //maximum length per string
    getstr(*str, length); //get string from the RS232
    putstr(*str); //return the string to the computer by RS232 for debugging
    if (strncmp (*str,"prox",strlen("prox")) == 0) //check wether four letters in the string are the same as the word "prox"
    {
        LCD_clearscreen(0xF00F);
        printf ("prox detected");
    }
    else if (strncmp (*str,"AA",strlen("AA")) == 0) //check wether two letters in the string are the same as the chars "AA"
    {
        LCD_clearscreen(0x0F0F);
        printf ("AA detected");
    }
}

这些是使用的RS232功能:

/*
 * p u t s t r
 *
 *  Send a string towards the RS232 port
 */
void putstr(char *s)
{
    while(*s != '\0')
    {
            putch(*s);
            s++;
    }
}

/*
 * p u t c h
 *
 *  Send a character towards the RS232 port
 */
void putch(char c)
{
    while(U1STAbits.UTXBF);     // Wait for space in the transmit buffer
    U1TXREG=c;
    if (debug) LCD_putc(c);
}

/*
 * g e t c
 *
 *  Receive a character of the RS232 port
 */
char getch(void)
{
    while(!has_c());    // Wait till data is available in the receive buffer
    return(U1RXREG);
}

/*
 * g e t s t r
 *
 * Receive a line with a maximum amount of characters
 * the line is closed with '\0'
 * the amount of received characters is returned
 */
 int getstr(char *buf, int size)
 {
    int i;

    for (i = 0 ; i < size-1 ; i++)
    {
        if ((buf[i++] = getch()) == '\n') break;
    }
    buf[i] = '\0';

    return(i);
}

当我在连接到终端的 Microchip 上使用这个程序时，我得到如下信息:

What I send:
abcdefgh

What I get back (in sets of 3 characters):
adbc.de.fg.h

Answer 1

问题是你如何声明你的字符串。现在，您声明了一个包含 20 个 char 指针的数组。我认为您应该将其声明为普通的 char 数组:

char str[20];

然后当您将数组传递给函数时，只需使用例如getstr(str, length);.