如何迭代由空格分隔的单词组成的字符串中的单词?
注意,我对C字符串函数或那种字符操作/访问不感兴趣。比起效率,我更喜欢优雅。我当前的解决方案:
#include <iostream>
#include <sstream>
#include <string>
using namespace std;
int main() {
string s = "Somewhere down the road";
istringstream iss(s);
do {
string subs;
iss >> subs;
cout << "Substring: " << subs << endl;
} while (iss);
}
虽然有一些答案提供了C++20解决方案,但自从发布以来,已经做了一些更改,并将其作为缺陷报告应用于C++20。正因为如此,解决方案变得更短、更好:
#include <iostream>
#include <ranges>
#include <string_view>
namespace views = std::views;
using str = std::string_view;
constexpr str text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
auto splitByWords(str input) {
return input
| views::split(' ')
| views::transform([](auto &&r) -> str {
return {r.begin(), r.end()};
});
}
auto main() -> int {
for (str &&word : splitByWords(text)) {
std::cout << word << '\n';
}
}
到今天为止,它仍然只在GCC的主干分支(Godbolt链接)上可用。它基于两个更改:P1391迭代器构造函数用于std::string_view和P2210 DR修复std::views::split以保留范围类型。
在C++23中,不需要任何转换样板,因为P1989向std::string_view:添加了一个范围构造函数
#include <iostream>
#include <ranges>
#include <string_view>
namespace views = std::views;
constexpr std::string_view text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
auto main() -> int {
for (std::string_view&& word : text | views::split(' ')) {
std::cout << word << '\n';
}
}
(螺栓连杆)
我使用以下方法
void split(string in, vector<string>& parts, char separator) {
string::iterator ts, curr;
ts = curr = in.begin();
for(; curr <= in.end(); curr++ ) {
if( (curr == in.end() || *curr == separator) && curr > ts )
parts.push_back( string( ts, curr ));
if( curr == in.end() )
break;
if( *curr == separator ) ts = curr + 1;
}
}
PlasmaHH,我忘记包含删除带有空格的标记的额外检查(curr>ts)。
根据Galik的回答,我做了这个。这大部分都在这里,所以我不必一遍又一遍地写。C++仍然没有原生拆分函数,这真是太疯狂了。特征:
应该很快。容易理解(我认为)。合并空节。使用多个分隔符(例如“\r\n”)很简单
#include <string>
#include <vector>
#include <algorithm>
std::vector<std::string> split(const std::string& s, const std::string& delims)
{
using namespace std;
vector<string> v;
// Start of an element.
size_t elemStart = 0;
// We start searching from the end of the previous element, which
// initially is the start of the string.
size_t elemEnd = 0;
// Find the first non-delim, i.e. the start of an element, after the end of the previous element.
while((elemStart = s.find_first_not_of(delims, elemEnd)) != string::npos)
{
// Find the first delem, i.e. the end of the element (or if this fails it is the end of the string).
elemEnd = s.find_first_of(delims, elemStart);
// Add it.
v.emplace_back(s, elemStart, elemEnd == string::npos ? string::npos : elemEnd - elemStart);
}
// When there are no more non-spaces, we are done.
return v;
}
这是我写的一个函数,帮助我做了很多事情。它在为WebSocket做协议时帮助了我。
using namespace std;
#include <iostream>
#include <vector>
#include <sstream>
#include <string>
vector<string> split ( string input , string split_id ) {
vector<string> result;
int i = 0;
bool add;
string temp;
stringstream ss;
size_t found;
string real;
int r = 0;
while ( i != input.length() ) {
add = false;
ss << input.at(i);
temp = ss.str();
found = temp.find(split_id);
if ( found != string::npos ) {
add = true;
real.append ( temp , 0 , found );
} else if ( r > 0 && ( i+1 ) == input.length() ) {
add = true;
real.append ( temp , 0 , found );
}
if ( add ) {
result.push_back(real);
ss.str(string());
ss.clear();
temp.clear();
real.clear();
r = 0;
}
i++;
r++;
}
return result;
}
int main() {
string s = "S,o,m,e,w,h,e,r,e, down the road \n In a really big C++ house. \n Lives a little old lady. \n That no one ever knew. \n She comes outside. \n In the very hot sun. \n\n\n\n\n\n\n\n And throws C++ at us. \n The End. FIN.";
vector < string > Token;
Token = split ( s , "," );
for ( int i = 0 ; i < Token.size(); i++) cout << Token.at(i) << endl;
cout << endl << Token.size();
int a;
cin >> a;
return a;
}
我编写了以下代码。您可以指定分隔符,它可以是字符串。结果类似于Java的String.split,结果中包含空字符串。
例如,如果我们调用split(“ABCPICKABCANYABCTWO:ABC”,“ABC”),结果如下:
0 <len:0>
1 PICK <len:4>
2 ANY <len:3>
3 TWO: <len:4>
4 <len:0>
代码:
vector <string> split(const string& str, const string& delimiter = " ") {
vector <string> tokens;
string::size_type lastPos = 0;
string::size_type pos = str.find(delimiter, lastPos);
while (string::npos != pos) {
// Found a token, add it to the vector.
cout << str.substr(lastPos, pos - lastPos) << endl;
tokens.push_back(str.substr(lastPos, pos - lastPos));
lastPos = pos + delimiter.size();
pos = str.find(delimiter, lastPos);
}
tokens.push_back(str.substr(lastPos, str.size() - lastPos));
return tokens;
}
值得一提的是,这里有另一种从输入字符串中提取令牌的方法,仅依赖于标准库设施。这是STL设计背后力量和优雅的一个例子。
#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>
#include <iterator>
int main() {
using namespace std;
string sentence = "And I feel fine...";
istringstream iss(sentence);
copy(istream_iterator<string>(iss),
istream_iterator<string>(),
ostream_iterator<string>(cout, "\n"));
}
可以使用相同的通用复制算法将提取的令牌插入到容器中,而不是将其复制到输出流中。
vector<string> tokens;
copy(istream_iterator<string>(iss),
istream_iterator<string>(),
back_inserter(tokens));
…或直接创建矢量:
vector<string> tokens{istream_iterator<string>{iss},
istream_iterator<string>{}};