如何初始化字符串数组的char指针数组c ++

Posted 2023-02-21

【中文标题】如何初始化字符串数组的char指针数组c ++

【英文标题】：how to initialize a char pointer array for an array of strings c++

【发布时间】：2015-03-05 19:14:54

【问题描述】：

所以我必须填写一个单词数组，以便稍后访问它们。例如：名词 = "boy", "girl", "house" 等。问题是我必须使用字符点数组。我已经尝试过了，但是它抛出了一个错误，说错误太多初始值设定项。这是代码

class Sentence

    private:
    char* article[sz];
    char* verb[sz];
    char* preposition[sz];
    char* noun[sz];

后来我像这样调用构造函数，但它没有填充它们。

Sentence::Sentence()

    article[10]  =  "the", "a", "one", "some", "any" ;
    verb[] =  "drove", "jumped", "ran", "walked", "skipped" ;
    preposition[] =  "to", "from", "over", "under", "on" ;
    noun[] =  "boy ", "girl", "dog", "town", "car" ;

【问题讨论】：

sz 在哪里定义？

@Perrin Hawver 何时何地设置 sz？

另外，您正在尝试静态初始化数组中的索引。那没有意义。去掉 10 和方括号。

sz 设置在程序的顶部，尽管我将其硬编码为 5，但它会抛出相同的错误。

@PerrinHawver 如果您要在这里提出此类问题，您应该提供MVCE 并在您的问题中发布确切的错误消息。

【参考方案1】：

你说：

我必须填写一个单词数组，以便稍后访问它们。

如果这是核心要求，最好使用std::vector<std::string> 而不是char* 的数组。

class Sentence

    public:
        Sentence();

    private:
        std::vector<std::string> articles;
        std::vector<std::string> verbs;
        std::vector<std::string> prepositions;
        std::vector<std::string> nouns;
;

您可以使用以下方法初始化成员：

Sentence::Sentence() : articles "the", "a", "one", "some", "any" ,
                       verbs "drove", "jumped", "ran", "walked", "skipped" ,
                       prepositions "to", "from", "over", "under", "on" ,
                       nouns "boy ", "girl", "dog", "town", "car" 

您只需在成员变量上使用push_back 即可将项目添加到集合中。

【参考方案2】：

如果sz 是一些常数，那么你可以写

#include <array>

//...

const size_t sz = 5;

class Sentence

    private:
    std::array<const char *, sz> article;
    std::array<const char *, sz> verb;
    std::array<const char *, sz> preposition;
    std::array<const char *, sz> noun;

//...

Sentence::Sentence()

    article  =  "the", "a", "one", "some", "any" ;
    verb =  "drove", "jumped", "ran", "walked", "skipped" ;
    preposition =  "to", "from", "over", "under", "on" ;
    noun =  "boy ", "girl", "dog", "town", "car" ;

否则，您可以使用 std::vector<const char *> 代替数组。

#include <vector>

//...


class Sentence

    private:
    std::vector<const char *> article;
    std::vector<const char *> verb;
    std::vector<const char *> preposition;
    std::vector<const char *> noun;

//...

Sentence::Sentence()

    article  =  "the", "a", "one", "some", "any" ;
    verb =  "drove", "jumped", "ran", "walked", "skipped" ;
    preposition =  "to", "from", "over", "under", "on" ;
    noun =  "boy ", "girl", "dog", "town", "car" ;

【参考方案3】：

如果你需要初始化这种固定大小的数组，你可以在构造函数的成员初始化列表中进行。在构造函数的主体中是不可能这样做的。

假设sz 被声明为例如

static const size_t sz = 10; 

您使用此语法使用构造函数初始化它们

Sentence::Sentence() 
: article "the", "a", "one", "some", "any" 
, verb "drove", "jumped", "ran", "walked", "skipped" 
, preposition "to", "from", "over", "under", "on" 
, noun  "boy ", "girl", "dog", "town", "car"  

或者考虑使用弗拉德的回答中提到的std::array<char,sz>，甚至是R. Sahu 提到的std::vector<std::string>。其中任何一个都应该接受这个初始化器语法。