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);
}
这是我的版本
#include <vector>
inline std::vector<std::string> Split(const std::string &str, const std::string &delim = " ")
{
std::vector<std::string> tokens;
if (str.size() > 0)
{
if (delim.size() > 0)
{
std::string::size_type currPos = 0, prevPos = 0;
while ((currPos = str.find(delim, prevPos)) != std::string::npos)
{
std::string item = str.substr(prevPos, currPos - prevPos);
if (item.size() > 0)
{
tokens.push_back(item);
}
prevPos = currPos + 1;
}
tokens.push_back(str.substr(prevPos));
}
else
{
tokens.push_back(str);
}
}
return tokens;
}
它适用于多字符分隔符。它防止空令牌进入结果。它使用单个标头。当您不提供分隔符时,它将字符串作为一个标记返回。如果字符串为空,它还会返回一个空结果。不幸的是,它的效率很低,因为存在巨大的std::vector副本,除非您使用C++11进行编译,否则应该使用移动示意图。在C++11中,这段代码应该很快。
短而优雅
#include <vector>
#include <string>
using namespace std;
vector<string> split(string data, string token)
{
vector<string> output;
size_t pos = string::npos; // size_t to avoid improbable overflow
do
{
pos = data.find(token);
output.push_back(data.substr(0, pos));
if (string::npos != pos)
data = data.substr(pos + token.size());
} while (string::npos != pos);
return output;
}
可以使用任何字符串作为分隔符,也可以与二进制数据一起使用(std::string支持二进制数据,包括空值)
使用:
auto a = split("this!!is!!!example!string", "!!");
输出:
this
is
!example!string
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;
}