使用argv和argc向函数发送参数

Question

有人能帮助我理解如何将参数发送到"lora_rf_config“函数吗？非常感谢！

我试着：

char cfgred[7][10]={'lora_rf_config','915000000','10','0','1','8','14'};
lora_rf_config(7,&cfgred);

我试图使用的功能是：

static void lora_rf_config(int argc, char *argv[])
{
    if (argc == 1) {      
        e_printf("OK%d,%d,%d,%d,%d,%d\r\n",  g_lora_config.lorap2p_param.Frequency, 
                                             g_lora_config.lorap2p_param.Spreadfact,
                                             g_lora_config.lorap2p_param.Bandwidth,
                                             g_lora_config.lorap2p_param.Codingrate,
                                             g_lora_config.lorap2p_param.Preamlen,
                                             g_lora_config.lorap2p_param.Powerdbm );
        return;
    } else {
        if (argc != 7) {
            out_error(RAK_ARG_ERR);
            return;
        }
    if (!(CHECK_P2P_FREQ(atoi(argv[1])) &&
             CHECK_P2P_SF(atoi(argv[2])) &&
             CHECK_P2P_BDW(atoi(argv[3])) &&
             CHECK_P2P_CR(atoi(argv[4])) &&
             CHECK_P2P_PREMLEN(atoi(argv[5])) &&
             CHECK_P2P_PWR(atoi(argv[6])))) {
            out_error(RAK_ARG_ERR);
        return;  
      } 

      if (read_partition(PARTITION_0, (char *)&g_lora_config, sizeof(g_lora_config)) < 0) {
          out_error(RAK_RD_CFG_ERR);
          return;
      }

      g_lora_config.lorap2p_param.Frequency = atoi(argv[1]);
      g_lora_config.lorap2p_param.Spreadfact = atoi(argv[2]);
      g_lora_config.lorap2p_param.Bandwidth = atoi(argv[3]);
      g_lora_config.lorap2p_param.Codingrate = atoi(argv[4]);
      g_lora_config.lorap2p_param.Preamlen = atoi(argv[5]);
      g_lora_config.lorap2p_param.Powerdbm = atoi(argv[6]);
      write_partition(PARTITION_0, (char *)&g_lora_config, sizeof(g_lora_config));
      e_printf("OK\r\n");
    }

    return;
}

我得到的错误是：

..\..\..\src\application\RAK811\app.c(107): error:  #26: too many characters in character constant
  char cfgred[7][10]={'lora_rf_config','915000000','10','0','1','8','14'};

我对这种争论没有经验。谢谢您抽时间见我。

Answer 1

lora_rf_config需要与main函数相同的参数:指向字符串的指针数组及其长度。

C中的字符串是指向char的指针，它们指向的char缓冲区具有终止NUL字符(如果NUL char缺失，那么它不是字符串，只是一个字符数组)。换句话说，C中不存在字符串类型，但是字符串的严格性取决于char数组或缓冲区中的实际数据。使用""字符串文字可以创建一个字符串，IOW除了您所写的内容之外，它还添加了终止NUL。

// cfgred is array([) of 7 pointers(*) to char.
// Note: string literals are read-only, so you must not modify these
// strings. If you want a modifiable string, this would be a bit more complex,
// but I think this is out of the scope of your question.
char *cfgred[7] = { "lora_rf_config" , "915000000", "10","0", "1", "8", "14"};

// you can get the number of elements in array by dividing its sizeof size (bytes)
// with the size of it's elements in bytes. Just make sure cfgred here is array...
// in the function it is pointer already (arrays get converted to pointers, so
// you can't do this inside the function, you have to do it where you still have
// the original array
int cfgred_len = sizeof cfgred / sizeof(cfgred[0]);

// when you pass array to function, it is automatically converted to pointer, 
// so you must not use & when passing an array like this, otherwise types don't
// match
lora_rf_config(cfgred_len, cfgred);

顺便提一下，总是打开编译器警告.他们帮了你很大的忙，修好了。对于gcc和clagn，使用-Wall -Wextra，对于Visual使用/W3或更好地使用/W4。然后修正你收到的任何警告，因为它们可能做不到你期望的事情。

Answer 2

初始化未正确完成，请尝试更改

char cfgred[7][10]={'lora_rf_config','915000000','10','0','1','8','14'};

转到

char cfgred[7][16]={"lora_rf_config","915000000","10","0","1","8","14"};