c - 了解strspn(const char * s，const char * accept)函数

我正在写一个程序，逐行读取一个文件，将单词和翻译分开。下面的代码有效。然而，我无法理解/* separate word and translation */函数的load_dictionary部分实际上是如何工作的。。
情况不明：
p line的输出
p word后的输出。不应该在word = line + strspn(line, DELIMS)\t和print-ants\t之前阅读。
文件：dict.txt

WORD    TRANSLATION

ants    anttt
anti    eti
ante    soggy
anda    eggs

功能：主

 /* maximum number of characters for word to search */
 #define WORD_MAX 256

 /* maximum number of characters in line */
 #ifndef LINE_MAX
 #define LINE_MAX 2048
 #endif

 int main(int argc, char * argv[]) {
        char word[WORD_MAX], * translation;
        int len;

        if (argc <= 1)
            return 0; /* no dictionary specified */

        /* load dictionary */
        load_dictionary(argv[1]);
        return 0;
  }

函数：加载词典：-读取词典文件

/* delimiter for dictionary */
#define DELIMS "\t"

unsigned void load_dictionary(const char * filename) {
        FILE * pfile;
        char line[LINE_MAX], * word, * translation;

        /* ensure file can be opened */
        if ( !(pfile = fopen(filename,"r")) )
            return icount;

        /* read lines */
        while ( (fgets(line, LINE_MAX, pfile)) ) {
            /* strip trailing newline */
            int len = strlen(line);
            if (len > 0 && line[len-1] == '\n') {
              line[len-1] = '\0';
              --len;
            }

            /* separate word and translation */
            word = line + strspn(line, DELIMS);

            if ( !word[0] )
                continue; /* no word in line */
            translation = word + strcspn(word, DELIMS);
            *translation++ = '\0';
            translation += strspn(translation, DELIMS);
        }
 }

最佳答案

strspn将给出DELIM中出现的初始字符数
strcspn将给出DELIM中不存在的初始字符数
（见http://man7.org/linux/man-pages/man3/strspn.3.html）
因此，代码的思想是使用简单的指针算法使word和translation指针指向输入中的第一个单词和输入中的第二个单词。此外，代码在第一个单词后面添加一个NUL终止符，使其看起来像两个字符串。
例子：

line: \t\t\t\tC++\0\t\t\tA programming language
              ^   ^      ^
              |   |      |
              |   |      translation points here
              |   |
              |   NUL added here
              |
              word points here

因此打印word和translation将给出：

C++
A programming language

附加注释的代码：

        word = line + strspn(line, DELIMS);  // Skip tabs, i.e.
                                             // make word point to the
                                             // first character which is
                                             // not a tab (aka \t)

        if ( !word[0] )
            continue; /* no word in line */

        translation = word + strcspn(word, DELIMS); // Make translation point to the
                                                    // first character after word
                                                    // which is a tab (aka \t), i.e. it
                                                    // points to the character just after
                                                    // the first word in line



        *translation++ = '\0';               // Add the NUL termination and
                                             // increment translation

        translation += strspn(translation, DELIMS);   // Skip tabs, i.e.
                                                      // make translation point to the
                                                      // second word in line which is

关于c - 了解strspn(const char * s，const char * accept)函数，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/57767867/