我创建了一个程序，该程序可以反转句子中每个单词的字母。我正在通过4行将文本输入到输入文本文件中。输出文本全部在一行上，但我需要这样，以便当输入转到下一行时，输出也是如此。
string reversed(string word)
{
int n;
for(int i=0; i<word.length()/2; i++)
{
swap(word[i],word[word.length()-1-i]);
}
return word;
}
int main()
{
ifstream in;
ofstream out;
in.open("input.txt");
out.open("output.txt");
string word;
while(in>>word){
out << reversed(word) << " ";
}
in.close();
out.close();
return 0;
}
输入示例：
Expecting the world to treat you fairly because you are a good person is a little like expecting the bull not to attack you because you are a vegetarian.
输出示例：
gnitcepxE eht dlrow ot taert uoy ylriaf esuaceb uoy era a doog nosrep si a elttil ekil gnitcepxe eht llub ton ot kcatta uoy esuaceb uoy era a nairategev.
答案 0 :(得分：1)
使用std::getline()从输入中读取文本的各个行，然后使用std::istringstream遍历每行的各个单词：
#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
#include <algorithm>
std::string reversed(std::string word) {
std::reverse(word.begin(), word.end());
return word;
}
int main() {
std::ifstream in("input.txt");
std::ofstream out("output.txt");
std::string line, word;
while (std::getline(in, line)) {
std::istringstream iss(line);
if (iss >> word) {
out << reversed(word);
while (iss >> word) {
out << " " << reversed(word);
}
}
out << std::endl;
}
return 0;
}
答案 1 :(得分：0)
我想有很多可能的解决方案。我将向您展示一段代码，该代码大量使用了std库，因此仅用几行代码就结束了。有趣的工作将仅在main函数中的3条代码语句中完成。不需要像do，while，for之类的循环结构或其他控制结构。
这更像是现代C ++风格。
#include <vector>
#include <string>
#include <iostream>
#include <fstream>
#include <iterator>
#include <regex>
#include <algorithm>
struct WordsInLine // The words in one line + proxy for output iterator
{
std::vector<std::string> wordsInLine; // Container for words in one line
friend std::ostream& operator<< (std::ostream& os, const WordsInLine& w) {
std::copy(
w.wordsInLine.begin(), w.wordsInLine.end(),
std::ostream_iterator<std::string>{os, " "});
return os;
}
};
// Make reading easier
using AllLines = std::vector<WordsInLine>;
struct Line // ! This is a proxy for the input_iterator !
{ // Input function. Read on line of text file and split it
friend std::istream& operator>>(std::istream& is, Line& line) {
std::string wholeLine;
std::regex space("[ \\.\\,]");
line.words.wordsInLine.clear();
std::getline(is, wholeLine); // Read one complete line and split it into parts
std::copy(
std::sregex_token_iterator(wholeLine.begin(), wholeLine.end(), space, -1),
std::sregex_token_iterator(),
std::back_inserter(line.words.wordsInLine)
);
return is;
}
operator WordsInLine() const { return words; } // cast to needed result
WordsInLine words; // Local storage for all words in line
};
int main()
{
std::ifstream inFileStream{ "r:\\input.txt" }; // Open input file. Will be closed by destructor
std::ofstream outFileStream{ "r:\\output.txt" }; // Open output file. Will be closed by destructor
// 1. Read complete input file into memory and organize it in words by lines
AllLines allLines{ std::istream_iterator<Line>(inFileStream), std::istream_iterator<Line>() };
// 2. For all lines: Reverse all words in a line
std::for_each(
allLines.begin(), allLines.end(),
[](WordsInLine& w) {
std::for_each(
w.wordsInLine.begin(), w.wordsInLine.end(),
[](std::string& s) { std::reverse(s.begin(), s.end()); }
);
}
);
// 3. Output result to file
std::copy(
allLines.begin(), allLines.end(),
std::ostream_iterator<WordsInLine>{outFileStream, "\n"}
);
return 0;
}
我将代理用于输入和输出迭代器。输入迭代器还解析行并提取所有单词。请注意：使用正则表达式时，我还会删除“。”。和“，”（在解析的单词中）。
反向操作是通过嵌套的std::for_each()和嵌套的lambda来实现的。
希望这会有所帮助。
答案 2 :(得分：0)
避免使用正则表达式的替代解决方案可以简单地反转每个单词（如果需要，class BlockchainUT : DescribeSpec({
var blockchain = Blockchain()
@BeforeEach
fun beforeEach() {
blockchain = Blockchain()
blockchain.addBlock(listOf("foo1", "bar1"))
blockchain.addBlock(listOf("foo2", "bar2"))
blockchain.addBlock(listOf("foo3", "bar3"))
}
describe("isValidChain()") {
context("when the chain does not start with the genesis block") {
blockchain.chain[0] = Block(
System.currentTimeMillis(),
"---",
"xxx",
listOf("foo", "bar"))
it("returns false") {
Blockchain.isValid(blockchain) shouldBe false
}
}
context("when the chain starts with the genesis block and has multiple blocks") {
context("and a lastHash reference has changed returns false") {
blockchain.chain[2] = Block(
blockchain.chain[2].timestamp,
"broken-lastHash",
blockchain.chain[2].hash,
blockchain.chain[2].data)
it("returns false") {
Blockchain.isValid(blockchain) shouldBe false
}
}
context("and the chain contains a block with an invalid field") {
blockchain.chain[2] = Block(
blockchain.chain[2].timestamp,
blockchain.chain[2].lastHash,
blockchain.chain[2].hash,
listOf("some-bad-and-evil-data"))
it("returns false") {
Blockchain.isValid(blockchain) shouldBe false
}
}
}
}
})
包含标点符号列表和.find_first_of()从该位置开始）。一种相当简单的方法是使用.erase()读取每一行，然后从该行创建一个getline，然后从stringstream中读取每个单词，然后输出到您的输出文件。可以使用一个简单的标志来控制每个单词之间的空格添加。
不删除标点符号的简短实现可能是：
stringstream示例输入文件
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
std::string reverse (const std::string& s)
{
return std::string (s.rbegin(), s.rend());
}
int main (int argc, char **argv)
{
std::string line; /* string to hold each line */
if (argc < 3) { /* validate 2 arguments given */
std::cerr << "error: insufficient input.\nusage: ifile ofile\n";
return 1;
}
std::ifstream ifs {argv[1]}; /* open input file */
std::ofstream ofs {argv[2]}; /* open output file */
while (getline (ifs, line)) { /* read each line */
std::istringstream ss {line}; /* create stringstream from line */
std::string word; /* string to hold word */
size_t wc = 0; /* flag to control space output */
while (ss >> word) /* read each word */
ofs << (wc++ ? " " : "") << reverse (word); /* output rev'ed */
ofs << '\n'; /* tidy up with newline */
}
}
示例用法
$ cat ../dat/captnjack.txt
This is a tale
Of Captain Jack Sparrow
A Pirate So Brave
On the Seven Seas.
示例输出文件
$ ./bin/words_reverse ../dat/captnjack.txt ../dat/captnjack_rev.txt
根据您的输入/输出信息进行编辑
如果要删除单词末尾的标点符号，可以使用$ cat ../dat/captnjack_rev.txt
sihT si a elat
fO niatpaC kcaJ worrapS
A etariP oS evarB
nO eht neveS .saeS
和.find_first_of()来删除。由于您现在将标点符号移到找到该单词的末尾，因此您需要先从该单词.erase()将该字符保存下来。然后，您可以在单词后面添加它。通过删除标点符号并将其移到单词的末尾，您可以执行以下操作：
.erase()示例输入文件
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
std::string reverse (const std::string& s)
{
return std::string (s.rbegin(), s.rend());
}
int main (int argc, char **argv)
{
std::string line; /* string to hold each line */
const std::string rmchars {".,!?"}; /* punctuation to remove */
if (argc < 3) { /* validate 2 arguments given */
std::cerr << "error: insufficient input.\nusage: ifile ofile\n";
return 1;
}
std::ifstream ifs {argv[1]}; /* open input file */
std::ofstream ofs {argv[2]}; /* open output file */
while (getline (ifs, line)) { /* read each line */
std::istringstream ss {line}; /* create stringstream from line */
std::string word; /* string to hold word */
size_t wc = 0; /* flag to control space output */
while (ss >> word) { /* read each word */
size_t rmpos = word.find_first_of (rmchars); /* index or npos */
char punc = 0; /* char to hold punctuation */
if (rmpos != std::string::npos) { /* if not npos */
punc = word[rmpos]; /* save punctuation char */
word.erase (rmpos); /* erase punctuation */
}
ofs << (wc++ ? " " : "") << reverse (word); /* output rev'ed */
if (punc)
ofs << (char)punc; /* output punctuation char */
}
ofs << '\n'; /* tidy up with newline */
}
}
示例用法
$ cat dat/sentences.txt
Expecting the world to treat you
fairly because you are a good person
is a little like expecting the bull not to
attack you because you are a vegetarian.
示例输出文件
$ ./bin/words_reverse_w_punc dat/sentences.txt dat/sentences_rev.txt
有很多方法可以解决此问题。您可以根据需要使它变得简单或复杂。