段落以单词为单位按行反序

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//

// 以单词为单位进行反序，按行进行，标点符合不反序. 例如：

// "ABC DEF GH.\nabc def gh."反序为"GH. DEF ABC\ngh. def abc"

//

// 方法：先将句子中字母倒置，然后将每个单词字母倒置，如下.

//       .HG FED CBA\n.hg fed cba

//       GH. DEF ABC\ngh. def abc

//

 

#include <cstdlib>

#include <cassert>

#include <iostream>

 

//

// 将单词字母倒置.

//

void reverse_word(char *word, size_t length)

{

    assert(NULL != word);

     

    char ch;

     

    for (size_t i = 0; i < length / 2; ++i)

    {

        ch = word[i];

        word[i] = word[length - 1 - i];

        word[length - 1 - i] = ch;

    }

}

 

 

//

// 将句子所有字母倒置.

//

void reverse_sentence(char *sentence, size_t length)

{

    size_t begin = 0;

     

    reverse_word(sentence, length);

    for (size_t offset = 0; offset < length; ++offset)

    {

        if (' ' == sentence[offset]) {

            reverse_word(sentence + begin, offset - begin);

            begin = offset + 1;

        }

    }

    reverse_word(sentence + begin, length - begin);

}

 

 

//

// 将段落中所有单词的字母倒置.

//

void reverse_section(char *section)

{

    assert(NULL != section);

     

    // 将各个句子单词倒置.

    for (size_t begin = 0, offset = 0; '\0' != section[offset]; ++offset)

    {

        if ('\n' == section[offset] || '\0' == section[offset])

        {

            reverse_sentence(section + begin, offset - begin);

            begin = offset + 1;

        }

    }

}

 

int main(void)

{

    char section[] = "ABC DEF GH.\nabc def gh.";

     

    reverse_section(section);

    std::cout << section << std::endl;

     

    return EXIT_SUCCESS;

}