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
这与其他答案相似，但它使用了string_view。这些是原始字符串的视图。类似于c++20的例子。虽然这将是一个c++17的例子。(编辑以跳过空匹配)
#include <algorithm>
#include <iostream>
#include <string_view>
#include <vector>
std::vector<std::string_view> split(std::string_view buffer,
const std::string_view delimeter = " ") {
std::vector<std::string_view> ret{};
std::decay_t<decltype(std::string_view::npos)> pos{};
while ((pos = buffer.find(delimeter)) != std::string_view::npos) {
const auto match = buffer.substr(0, pos);
if (!match.empty()) ret.push_back(match);
buffer = buffer.substr(pos + delimeter.size());
}
if (!buffer.empty()) ret.push_back(buffer);
return ret;
}
int main() {
const auto split_values = split("1 2 3 4 5 6 7 8 9 10 ");
std::for_each(split_values.begin(), split_values.end(),
[](const auto& str) { std::cout << str << '\n'; });
return split_values.size();
}
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());
}
我会使用boost::tokenizer。下面的文档解释了如何创建适当的标记器函数:http://www.boost.org/doc/libs/1_52_0/libs/tokenizer/tokenizerfunction.htm
这里有一个对你的案子有用。
struct my_tokenizer_func
{
template<typename It>
bool operator()(It& next, It end, std::string & tok)
{
if (next == end)
return false;
char const * del = ">=";
auto pos = std::search(next, end, del, del + 2);
tok.assign(next, pos);
next = pos;
if (next != end)
std::advance(next, 2);
return true;
}
void reset() {}
};
int main()
{
std::string to_be_parsed = "1) one>=2) two>=3) three>=4) four";
for (auto i : boost::tokenizer<my_tokenizer_func>(to_be_parsed))
std::cout << i << '\n';
}
作为奖励，这里有一个分割函数和宏的代码示例，很容易使用，你可以在其中选择容器类型:
#include <iostream>
#include <vector>
#include <string>
#define split(str, delim, type) (split_fn<type<std::string>>(str, delim))
template <typename Container>
Container split_fn(const std::string& str, char delim = ' ') {
Container cont{};
std::size_t current, previous = 0;
current = str.find(delim);
while (current != std::string::npos) {
cont.push_back(str.substr(previous, current - previous));
previous = current + 1;
current = str.find(delim, previous);
}
cont.push_back(str.substr(previous, current - previous));
return cont;
}
int main() {
auto test = std::string{"This is a great test"};
auto res = split(test, ' ', std::vector);
for(auto &i : res) {
std::cout << i << ", "; // "this", "is", "a", "great", "test"
}
return 0;
}
对于字符串分隔符
基于字符串分隔符拆分字符串。如分割字符串“adsf-+qwret-+nvfkbdsj-+orthdfjgh-+dfjrleih”基于字符串分隔符“-+”，输出将是{“adsf”，“qwret”，“nvfkbdsj”，“orthdfjgh”，“dfjrleih”}
#include <iostream>
#include <sstream>
#include <vector>
using namespace std;
// for string delimiter
vector<string> split (string s, string delimiter) {
size_t pos_start = 0, pos_end, delim_len = delimiter.length();
string token;
vector<string> res;
while ((pos_end = s.find (delimiter, pos_start)) != string::npos) {
token = s.substr (pos_start, pos_end - pos_start);
pos_start = pos_end + delim_len;
res.push_back (token);
}
res.push_back (s.substr (pos_start));
return res;
}
int main() {
string str = "adsf-+qwret-+nvfkbdsj-+orthdfjgh-+dfjrleih";
string delimiter = "-+";
vector<string> v = split (str, delimiter);
for (auto i : v) cout << i << endl;
return 0;
}
adsf qwret nvfkbdsj orthdfjgh dfjrleih
对于单字符分隔符
基于字符分隔符拆分字符串。例如，使用分隔符“+”分割字符串“adsf+qwer+poui+fdgh”将输出{“adsf”，“qwer”，“poui”，“fdgh”}
#include <iostream>
#include <sstream>
#include <vector>
using namespace std;
vector<string> split (const string &s, char delim) {
vector<string> result;
stringstream ss (s);
string item;
while (getline (ss, item, delim)) {
result.push_back (item);
}
return result;
}
int main() {
string str = "adsf+qwer+poui+fdgh";
vector<string> v = split (str, '+');
for (auto i : v) cout << i << endl;
return 0;
}
adsf qwer poui fdgh
由于这是c++分割字符串或类似的顶级Stack Overflow谷歌搜索结果，我将发布一个完整的、复制/粘贴可运行的示例，展示这两种方法。
splitString使用stringstream(在大多数情况下可能是更好更简单的选项)
splitString2使用find和substr(一种更手动的方法)
// SplitString.cpp
#include <iostream>
#include <vector>
#include <string>
#include <sstream>
// function prototypes
std::vector<std::string> splitString(const std::string& str, char delim);
std::vector<std::string> splitString2(const std::string& str, char delim);
std::string getSubstring(const std::string& str, int leftIdx, int rightIdx);
int main(void)
{
// Test cases - all will pass
std::string str = "ab,cd,ef";
//std::string str = "abcdef";
//std::string str = "";
//std::string str = ",cd,ef";
//std::string str = "ab,cd,"; // behavior of splitString and splitString2 is different for this final case only, if this case matters to you choose which one you need as applicable
std::vector<std::string> tokens = splitString(str, ',');
std::cout << "tokens: " << "\n";
if (tokens.empty())
{
std::cout << "(tokens is empty)" << "\n";
}
else
{
for (auto& token : tokens)
{
if (token == "") std::cout << "(empty string)" << "\n";
else std::cout << token << "\n";
}
}
return 0;
}
std::vector<std::string> splitString(const std::string& str, char delim)
{
std::vector<std::string> tokens;
if (str == "") return tokens;
std::string currentToken;
std::stringstream ss(str);
while (std::getline(ss, currentToken, delim))
{
tokens.push_back(currentToken);
}
return tokens;
}
std::vector<std::string> splitString2(const std::string& str, char delim)
{
std::vector<std::string> tokens;
if (str == "") return tokens;
int leftIdx = 0;
int delimIdx = str.find(delim);
int rightIdx;
while (delimIdx != std::string::npos)
{
rightIdx = delimIdx - 1;
std::string token = getSubstring(str, leftIdx, rightIdx);
tokens.push_back(token);
// prep for next time around
leftIdx = delimIdx + 1;
delimIdx = str.find(delim, delimIdx + 1);
}
rightIdx = str.size() - 1;
std::string token = getSubstring(str, leftIdx, rightIdx);
tokens.push_back(token);
return tokens;
}
std::string getSubstring(const std::string& str, int leftIdx, int rightIdx)
{
return str.substr(leftIdx, rightIdx - leftIdx + 1);
}
