我在c++中使用以下方法解析字符串:
using namespace std;
string parsed,input="text to be parsed";
stringstream input_stringstream(input);
if (getline(input_stringstream,parsed,' '))
{
// do some processing.
}
使用单个字符分隔符进行解析是可以的。但是如果我想使用字符串作为分隔符呢?
例子:我想拆分:
scott>=tiger
用>=作为分隔符，这样我就可以得到斯科特和老虎。
当前回答
功能:
std::vector<std::string> WSJCppCore::split(const std::string& sWhat, const std::string& sDelim) {
std::vector<std::string> vRet;
size_t nPos = 0;
size_t nLen = sWhat.length();
size_t nDelimLen = sDelim.length();
while (nPos < nLen) {
std::size_t nFoundPos = sWhat.find(sDelim, nPos);
if (nFoundPos != std::string::npos) {
std::string sToken = sWhat.substr(nPos, nFoundPos - nPos);
vRet.push_back(sToken);
nPos = nFoundPos + nDelimLen;
if (nFoundPos + nDelimLen == nLen) { // last delimiter
vRet.push_back("");
}
} else {
std::string sToken = sWhat.substr(nPos, nLen - nPos);
vRet.push_back(sToken);
break;
}
}
return vRet;
}
单元测试:
bool UnitTestSplit::run() {
bool bTestSuccess = true;
struct LTest {
LTest(
const std::string &sStr,
const std::string &sDelim,
const std::vector<std::string> &vExpectedVector
) {
this->sStr = sStr;
this->sDelim = sDelim;
this->vExpectedVector = vExpectedVector;
};
std::string sStr;
std::string sDelim;
std::vector<std::string> vExpectedVector;
};
std::vector<LTest> tests;
tests.push_back(LTest("1 2 3 4 5", " ", {"1", "2", "3", "4", "5"}));
tests.push_back(LTest("|1f|2п|3%^|44354|5kdasjfdre|2", "|", {"", "1f", "2п", "3%^", "44354", "5kdasjfdre", "2"}));
tests.push_back(LTest("|1f|2п|3%^|44354|5kdasjfdre|", "|", {"", "1f", "2п", "3%^", "44354", "5kdasjfdre", ""}));
tests.push_back(LTest("some1 => some2 => some3", "=>", {"some1 ", " some2 ", " some3"}));
tests.push_back(LTest("some1 => some2 => some3 =>", "=>", {"some1 ", " some2 ", " some3 ", ""}));
for (int i = 0; i < tests.size(); i++) {
LTest test = tests[i];
std::string sPrefix = "test" + std::to_string(i) + "(\"" + test.sStr + "\")";
std::vector<std::string> vSplitted = WSJCppCore::split(test.sStr, test.sDelim);
compareN(bTestSuccess, sPrefix + ": size", vSplitted.size(), test.vExpectedVector.size());
int nMin = std::min(vSplitted.size(), test.vExpectedVector.size());
for (int n = 0; n < nMin; n++) {
compareS(bTestSuccess, sPrefix + ", element: " + std::to_string(n), vSplitted[n], test.vExpectedVector[n]);
}
}
return bTestSuccess;
}
其他回答
Strtok允许您传入多个字符作为分隔符。我敢打赌，如果你传入“>=”，你的示例字符串将被正确分割(即使>和=被算作单独的分隔符)。
EDIT如果您不想使用c_str()将字符串转换为char*，您可以使用substr和find_first_of进行标记化。
string token, mystring("scott>=tiger");
while(token != mystring){
token = mystring.substr(0,mystring.find_first_of(">="));
mystring = mystring.substr(mystring.find_first_of(">=") + 1);
printf("%s ",token.c_str());
}
答案已经在那里，但选择答案使用擦除功能，这是非常昂贵的，想想一些非常大的字符串(以mb为单位)。因此我使用下面的函数。
vector<string> split(const string& i_str, const string& i_delim)
{
vector<string> result;
size_t startIndex = 0;
for (size_t found = i_str.find(i_delim); found != string::npos; found = i_str.find(i_delim, startIndex))
{
result.emplace_back(i_str.begin()+startIndex, i_str.begin()+found);
startIndex = found + i_delim.size();
}
if (startIndex != i_str.size())
result.emplace_back(i_str.begin()+startIndex, i_str.end());
return result;
}
你也可以使用regex:
std::vector<std::string> split(const std::string str, const std::string regex_str)
{
std::regex regexz(regex_str);
std::vector<std::string> list(std::sregex_token_iterator(str.begin(), str.end(), regexz, -1),
std::sregex_token_iterator());
return list;
}
这相当于:
std::vector<std::string> split(const std::string str, const std::string regex_str)
{
std::sregex_token_iterator token_iter(str.begin(), str.end(), regexz, -1);
std::sregex_token_iterator end;
std::vector<std::string> list;
while (token_iter != end)
{
list.emplace_back(*token_iter++);
}
return list;
}
像这样使用它:
#include <iostream>
#include <string>
#include <regex>
std::vector<std::string> split(const std::string str,
const std::string regex_str) {
std::regex regexz(regex_str);
return {std::sregex_token_iterator(str.begin(), str.end(), regexz, -1),
std::sregex_token_iterator()};
}
int main()
{
std::string input_str = "lets split this";
std::string regex_str = " ";
auto tokens = split(input_str, regex_str);
for (auto& item: tokens)
{
std::cout<<item <<std::endl;
}
}
在网上玩!
您可以简单地使用子字符串、字符等，或者使用实际的正则表达式来进行分割。 它也是简洁的c++ 11!
我使用指针算术。对于字符串delim，如果你对char delim满意，只需简单地删除Inner while。我希望它是正确的。如果你发现任何错误或改进，请留下评论。
std::vector<std::string> split(std::string s, std::string delim)
{
char *p = &s[0];
char *d = &delim[0];
std::vector<std::string> res = {""};
do
{
bool is_delim = true;
char *pp = p;
char *dd = d;
while (*dd && is_delim == true)
if (*pp++ != *dd++)
is_delim = false;
if (is_delim)
{
p = pp - 1;
res.push_back("");
}
else
*(res.rbegin()) += *p;
} while (*p++);
return res;
}
这个方法使用字符串find和字符串substr
vector<string> split(const string& str,const string delim){
vector<string> vtokens;
size_t start = 0;
size_t end = 0;
while((end = str.find(delim,start))!=string::npos){
vtokens.push_back(str.substr(start,end-start));
start = end +1;
}
vtokens.push_back(str.substr(start));
return vtokens;
}
