LANGUAGE » CPP

String

Last updated:
Reference:cplusplus.com

Usage ​

cpp
#include <string>

Contains ​

Check if text contains substr:

cpp
if (text.find(substr) != std::string::npos) {
    fmt::println("Substring found!");
} else {
    fmt::println("Substring not found!");
}

Trim ​

In place whitespace trim of a std::string:

cpp
const std::string WHITESPACE = " \n\r\t\f\v";

void ltrim(std::string &s) {
    s.erase(s.begin(), s.begin() + s.find_first_not_of(WHITESPACE));
}

void rtrim(std::string &s) {
    s.erase(s.begin() + s.find_last_not_of(WHITESPACE) + 1, s.end());
}

void trim(std::string &s) {
    ltrim(s);
    rtrim(s);
}

Copy of a std::string with the whitespace trimmed:

cpp
const std::string WHITESPACE = " \n\r\t\f\v";

std::string ltrim(const std::string &s) {
    size_t start = s.find_first_not_of(WHITESPACE);
    return (start == std::string::npos) ? "" : s.substr(start);
}

std::string rtrim(const std::string &s) {
    size_t end = s.find_last_not_of(WHITESPACE);
    return (end == std::string::npos) ? "" : s.substr(0, end + 1);
}

std::string trim(const std::string &s) {
    size_t start = s.find_first_not_of(WHITESPACE);
    if (start == std::string::npos) {
        return "";
    }
    size_t end = s.find_last_not_of(WHITESPACE);
    return s.substr(start, end - start + 1);
}

Replace ​

Using regex replace to trim whitespace of a std::string:

cpp
#include <regex>

std::string ltrim(const std::string &s) {
    return std::regex_replace(s, std::regex("^\\s+"), std::string(""));
}

std::string rtrim(const std::string &s) {
    return std::regex_replace(s, std::regex("\\s+$"), std::string(""));
}

std::string trim(const std::string &s) {
    return ltrim(rtrim(s));
}