UOX3.org

#include <iostream>
#include <algorithm>
#include <regex>
#include <string>
#include <ctype.h>
#include <chrono>
// Regex way to trim
std::string ltrim(const std::string& s) {
    return std::regex_replace(s, std::regex("^\\s+"), std::string(""));
}
// string search and find way to trim
std::string lltrim(const std::string& s) {
    auto loc = s.find_first_not_of(" \t\f\r\v\n");
    if (loc == std::string::npos){
        return std::string();
    }
    else {
        return s.substr(loc) ;
    }
}
// for way to trim
std::string llltrim(const std::string& s) {
    auto count = 0 ;
    for (auto &c : s) {
        if (!isspace(c)){
            return s.substr(count) ;
        }
        else {
            count++;
        }
    }

    return std::string();
   
}


int main(int argc, const char * argv[]) {
   
    std::string test = "        Howdy";
    // Measure one way
    auto start_time = std::chrono::steady_clock::now();
    auto a = ltrim(test);
    auto end = std::chrono::steady_clock::now();
    auto diff = end - start_time ;
    std::cout <<"ltrim of " << test<<" return '"<<a<<"' in "<< std::chrono::duration_cast<std::chrono::microseconds>(diff).count() << " usec" << std::endl;

    // Measure  way
    start_time = std::chrono::steady_clock::now();
    a = llltrim(test);
    end = std::chrono::steady_clock::now();
    diff = end - start_time ;
    std::cout <<"llltrim of " << test<< " return '"<<a<<"' in "<< std::chrono::duration_cast<std::chrono::microseconds>(diff).count() << " usec" << std::endl;

    // Measure  way
    start_time = std::chrono::steady_clock::now();
    a = lltrim(test);
    end = std::chrono::steady_clock::now();
    diff = end - start_time ;
    std::cout <<"lltrim of " << test<< " return '"<<a<<"' in "<< std::chrono::duration_cast<std::chrono::microseconds>(diff).count()  << " usec" << std::endl;


}