在C++中标记字符串介绍详细指南

本文概述

C ++
C ++
C
CPP
C ++

标记字符串表示相对于某些定界符分割字符串。有很多标记字符串的方法。在本文中, 将对其中的四个进行说明：
使用stringstream
一种
串流
将字符串对象与流相关联, 使你可以像对待流一样读取字符串。
以下是C ++实现：
C ++

// Tokenizing a string using stringstream #include < bits/stdc++.h> using namespace std; int main() {string line = "lsbin is a must try" ; // Vector of string to save tokens vector < string> tokens; // stringstream class check1 stringstream check1(line); string intermediate; // Tokenizing w.r.t. space ' ' while (getline(check1, intermediate, ' ' )) { tokens.push_back(intermediate); }// Printing the token vector for ( int i = 0; i < tokens.size(); i++) cout < < tokens[i] < < '\n' ; }

输出如下

lsbinisamusttry

使用strtok()

// Splits str[] according to given delimiters.// and returns next token. It needs to be called// in a loop to get all tokens. It returns NULL// when there are no more tokens.char * strtok(char str[], const char *delims);

以下是C ++实现：
C ++

// C/C++ program for splitting a string // using strtok() #include < stdio.h> #include < string.h> int main() { char str[] = "Geeks-for-Geeks" ; // Returns first token char *token = strtok (str, "-" ); // Keep printing tokens while one of the // delimiters present in str[]. while (token != NULL) { printf ( "%s\n" , token); token = strtok (NULL, "-" ); }return 0; }

输出如下

GeeksforGeeks

strtok()的另一个示例：
C

// C code to demonstrate working of // strtok #include < string.h> #include < stdio.h> // Driver function int main() { // Declaration of string char gfg[100] = " Geeks - for - geeks - Contribute" ; // Declaration of delimiter const char s[4] = "-" ; char * tok; // Use of strtok // get first token tok = strtok (gfg, s); // Checks for delimeter while (tok != 0) { printf ( " %s\n" , tok); // Use of strtok // go through other tokens tok = strtok (0, s); }return (0); }

输出如下

Geeks for geeks Contribute

使用strtok_r()
就像C中的strtok()函数一样,
strtok_r()
执行将字符串解析为令牌序列的相同任务。 strtok_r()是strtok()的可重入版本。
有两种方法可以调用strtok_r()

// The third argument saveptr is a pointer to a char * // variable that is used internally by strtok_r() in // order to maintain context between successive calls// that parse the same string.char *strtok_r(char *str, const char *delim, char **saveptr);

下面是一个简单的C ++程序, 用于显示strtok_r()的用法：
CPP

// C/C++ program to demonstrate working of strtok_r() // by splitting string based on space character. #include< stdio.h> #include< string.h> int main() { char str[] = "Geeks for Geeks" ; char *token; char *rest = str; while ((token = strtok_r(rest, " " , & rest))) printf ( "%s\n" , token); return (0); }

输出如下

GeeksforGeeks

使用std :: sregex_token_iterator
在这种方法中, 基于正则表达式匹配进行标记化。当需要多个定界符时, 更适合用例。
下面是一个简单的C ++程序, 用于显示std :: sregex_token_iterator的用法：
C ++

// CPP program for above approach #include < iostream> #include < regex> #include < string> #include < vector> /** * @brief Tokenize the given vector according to the regex * and remove the empty tokens. * * @param str * @param re * @return std::vector< std::string> */ std::vector< std::string> tokenize( const std::string str, const std::regex re) { std::sregex_token_iterator it{ str.begin(), str.end(), re, -1 }; std::vector< std::string> tokenized{ it, {} }; // Additional check to remove empty strings tokenized.erase( std::remove_if(tokenized.begin(), tokenized.end(), [](std::string const & s) { return s.size() == 0; }), tokenized.end()); return tokenized; }// Driver Code int main() { const std::string str = "Break string a, spaces, and, commas"; const std::regex re(R "([\s|, ]+)" ); // Function Call const std::vector< std::string> tokenized = tokenize(str, re); for (std::string token : tokenized) std::cout < < token < < std::endl; return 0; }

【在C++中标记字符串介绍详细指南】输出如下