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);
}
使用vector作为基类的快速版本,可完全访问其所有运算符:
// Split string into parts.
class Split : public std::vector<std::string>
{
public:
Split(const std::string& str, char* delimList)
{
size_t lastPos = 0;
size_t pos = str.find_first_of(delimList);
while (pos != std::string::npos)
{
if (pos != lastPos)
push_back(str.substr(lastPos, pos-lastPos));
lastPos = pos + 1;
pos = str.find_first_of(delimList, lastPos);
}
if (lastPos < str.length())
push_back(str.substr(lastPos, pos-lastPos));
}
};
用于填充STL集的示例:
std::set<std::string> words;
Split split("Hello,World", ",");
words.insert(split.begin(), split.end());
并不是说我们需要更多的答案,但这是我受到埃文·特兰启发后想到的。
std::vector <std::string> split(const string &input, auto delimiter, bool skipEmpty=true) {
/*
Splits a string at each delimiter and returns these strings as a string vector.
If the delimiter is not found then nothing is returned.
If skipEmpty is true then strings between delimiters that are 0 in length will be skipped.
*/
bool delimiterFound = false;
int pos=0, pPos=0;
std::vector <std::string> result;
while (true) {
pos = input.find(delimiter,pPos);
if (pos != std::string::npos) {
if (skipEmpty==false or pos-pPos > 0) // if empty values are to be kept or not
result.push_back(input.substr(pPos,pos-pPos));
delimiterFound = true;
} else {
if (pPos < input.length() and delimiterFound) {
if (skipEmpty==false or input.length()-pPos > 0) // if empty values are to be kept or not
result.push_back(input.substr(pPos,input.length()-pPos));
}
break;
}
pPos = pos+1;
}
return result;
}
对于一个大得离谱而且可能是冗余的版本,可以尝试很多For循环。
string stringlist[10];
int count = 0;
for (int i = 0; i < sequence.length(); i++)
{
if (sequence[i] == ' ')
{
stringlist[count] = sequence.substr(0, i);
sequence.erase(0, i+1);
i = 0;
count++;
}
else if (i == sequence.length()-1) // Last word
{
stringlist[count] = sequence.substr(0, i+1);
}
}
它并不漂亮,但总的来说(除了标点符号和一系列其他错误)它是有效的!
使用std::stringstream非常好,并且完全符合您的要求。如果您只是在寻找不同的方法,那么可以使用std::find()/std::find_first_of()和std::string::substr()。
下面是一个示例:
#include <iostream>
#include <string>
int main()
{
std::string s("Somewhere down the road");
std::string::size_type prev_pos = 0, pos = 0;
while( (pos = s.find(' ', pos)) != std::string::npos )
{
std::string substring( s.substr(prev_pos, pos-prev_pos) );
std::cout << substring << '\n';
prev_pos = ++pos;
}
std::string substring( s.substr(prev_pos, pos-prev_pos) ); // Last word
std::cout << substring << '\n';
return 0;
}