Question

创建一个程序，用户可以输入单词，然后弹出一个首字母缩写词，这很简单，但是我必须使用字典，并且必须使用键使首字母缩写词出现NullReferenceException不明白为什么看不到空

仅使用Visual Studio 2015，我已经尝试了很多，甚至都无法描述问题

    private string fullSentence;
    private string[] words = new string[5];
    private Dictionary<char, string> acronymDictionary = new Dictionary<char, string>();
    public Acronym(string sentence)
    {
        fullSentence = sentence;
        string[] words = sentence.Split(' ');

    }

    public void BuildAcronym()
    {

        char[] key = new char[words.Length];
        //key = null;
        //foreach (string info in words)
        //{
            for (int i = 0; i < words.Length; i++)
            {
                key[i] = Convert.ToChar(words[i].Substring(0,1)); //this is where the problem is
            }

我希望它能够运行，尤其是对于chars []键来说，它是由word []中每个单词的首字母填充的，因此我可以将key []设置为字典的键

Answer 1

run可以为null。

您可以在引发的行上放置一个断点，然后在“监视”窗口中检查words[i]的值。

Answer 2

请尝试这个。

    private string fullSentence;
    private string[] words;
    private Dictionary<char, string> acronymDictionary = new Dictionary<char, string>();
    public Acronym(string sentence)
    {
        fullSentence = sentence;
        words = sentence.Split(' ');

    }

    public void BuildAcronym()
    {
        if(words != null)
        { 
        char[] key = new char[words.Length];
        //key = null;
        //foreach (string info in words)
        //{
            for (int i = 0; i < words.Length; i++)
            {
                key[i] = Convert.ToChar(words[i].Substring(0,1)); //this is where the problem is
            }
         }
     }

为什么给我NullReferenceException但没有错误

2 个答案: