Question

typedef struct _String {
    char storage[40];
} string;

// Create a new `String`, from a C-style null-terminated array of
// characters.
String newString (char *str) {
//INSERT CODE HERE
    *str = malloc(1 * sizeof(string));




}

这是ADT的一部分，我无法理解我需要做什么。我知道我需要通过指针访问数组，但我不确定接下来我需要做什么。

Answer 1

如果您尝试将char*转换为新的String数据类型，则只需使用现有的C调用直接复制数据，请参阅here：< / p>

#include <string.h>

#define STRING_MAX  40

typedef struct _String
{
    char storage[STRING_MAX];
} String;

String newString (char *str)
{
  String s;

  // Make sure that 'str' is small enough to fit into String.
  if(strlen(str) < STRING_MAX)
  {
    strcpy(s.storage, str); // Use the built-in C libraries.
  }      
  else
  {
    s.storage[0] = '\0'; // Default to a null string.
  }

  return s;
}

或者：

String newString(char* str)
{
  String s;
  int i = 0;

  // Copy over every character and be sure not to go out of
  // bounds STRING_MAX and stop once a null is reached.
  while(i < STRING_MAX && str[i] != '\0')
  {
    s.storage[i] = str[i];
    i++;
  }

  // If the copy finished then put a null at the end since we skipped
  // copying it before in the WHILE loop.
  if(i < STRING_MAX)
  {
    s.storage[i] = '\0';
  }
}

创建一个新的字符串ADT

1 个答案: