C++ · std::string

std::string is the C++ string class, and it’s far easier to use than raw char* C strings. Differences from Python I noticed:

• It is mutable, so s[0] = 'p' works.
• substr(pos, len) takes a length, not an end index.
• find returns std::string::npos when nothing is found.
• + and += concatenate. std::to_string(n) and std::stoi(s) convert between numbers and strings.
• Comparing with == compares the contents, which isn’t true for C-string pointers.

#include <algorithm>
#include <cctype>
#include <iostream>
#include <string>

int main() {
    std::string s = "Pandit Deendayal Energy University";
    std::cout << s.size() << " chars, first word: " << s.substr(0, s.find(' ')) << '\n';

    auto pos = s.find("Energy");
    std::cout << "Energy at " << pos << '\n';
    std::cout << "missing: " << (s.find("Python") == std::string::npos) << '\n';

    s[0] = 'p';                                   // mutable
    std::string upper = s;
    std::transform(upper.begin(), upper.end(), upper.begin(),
                   [](unsigned char c) { return std::toupper(c); });
    std::cout << s << "\n" << upper << '\n';

    std::string id = "ICT" + std::to_string(2023);
    int year = std::stoi("2027");
    std::cout << id << ", graduating " << year << ", equal? " << (id == "ICT2023") << '\n';
}

Output:

34 chars, first word: Pandit
Energy at 17
missing: 1
pandit Deendayal Energy University
PANDIT DEENDAYAL ENERGY UNIVERSITY
ICT2023, graduating 2027, equal? 1