c - Libconfig 和 unsigned long。UL如何操作？

Question

我有一个问题：

name = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
// Store inventory:
params =
{
  myparams= ( {  max_len  = 1024UL;
              author = "Robert Louis Stevenson";
              price  = 29.99;
              qty    = 5; }
                );
            };

你知道如何从主这个值 1024UL 中检索吗？它不是整数，而是特定的 int（无符号长整数）。我还没有找到这样做的功能。您可以看到函数 config_setting_lookup_int，但显然它不起作用，因为要检索的值不是 int (1024UL)。谢谢大家的帮助！

config_t cfg;
config_setting_t *setting;
const char *str;
config_init(&cfg);

/* Read the file. If there is an error, report it and exit. */
if(! config_read_file(&cfg, "file.cfg"))
{
fprintf(stderr, "%s:%d - %s\n", config_error_file(&cfg),
        config_error_line(&cfg), config_error_text(&cfg));
config_destroy(&cfg);
return(EXIT_FAILURE);
}else{
printf("Config file is OK\n");
}

    /* Get the store name. */
        if(config_lookup_string(&cfg, "name", &str))
        printf("Store name: %s\n\n", str);
        else
        fprintf(stderr, "No 'name' setting in configuration file.\n");
    
    
    
        setting = config_lookup(&cfg, "params.myparams");
      if(setting != NULL)
      {
        int count = config_setting_length(setting);
        int i;
    
        printf("%-30s  %-30s   %-6s  %s\n", "TITLE", "AUTHOR", "PRICE", "QTY");
    
        for(i = 0; i < count; ++i)
        {
          config_setting_t *book = config_setting_get_elem(setting, i);
    
          /* Only output the record if all of the expected fields are present. */
          const char *author;
          int max_len;
          double price;
          int qty;
    
          if(!(config_setting_lookup_int(book, "max_len", &max_len)
               && config_setting_lookup_string(book, "author", &author)
               && config_setting_lookup_float(book, "price", &price)
               && config_setting_lookup_int(book, "qty", &qty)))
            continue;
    
          printf("%-30d  %-30s  $%6.2f  %3d\n", max_len, author, price, qty);
        }
        putchar('\n');
      }

标签： ctypesbyteunsignedlibconfig

Answer 1

• UL suffix meas that the constant integer has type unsigned long
• ULL - 'unsigned long long'
• U - unsigned int
• L - long int`
• LL - long long int`

It is better to have too long one that is needed, than a too short. In most cases, the compiler will convert it to the correct type.