Functions and collections · Lesson 8 of 21

Strings and arrays

std::string and its methods, fixed arrays, and std::array.

9 minutes2 games

std::string is text that grows and shrinks by itself, with many ready-made methods. Its characters are indexed from zero, just like arrays.

C++

#include <iostream>
#include <string>

int main() {
    std::string course = "SeaCode C++";
    std::cout << course.size() << " chars\n";
    std::cout << course[0] << " ... " << course.back() << "\n";
    std::cout << course.substr(0, 7) << "\n";          // from 0, take 7

    std::size_t pos = course.find("C++");
    if (pos != std::string::npos) std::cout << "found at " << pos << "\n";

    course += " track";
    course[0] = 's';
    std::cout << course << "\n";
    return 0;
}

course =

S[0]

e[1]

a[2]

C[3]

o[4]

d[5]

e[6]

[7]

C[8]

+[9]

+[10]

find("C++") found it at index 8.

Arrays

C++

#include <iostream>
#include <array>

int main() {
    int raw[4] = {90, 75, 88, 60};         // C-style array: fixed size
    std::array<int, 4> scores = {90, 75, 88, 60};

    int best = scores[0];
    for (std::size_t i = 1; i < scores.size(); i++) {
        if (scores[i] > best) best = scores[i];
    }
    std::cout << "best " << best << " of " << scores.size() << "\n";
    std::cout << "raw[2] = " << raw[2] << "\n";
    return 0;
}

What's the output?

#include <iostream>
#include <string>
int main() {
    std::string s = "algorithm";
    std::cout << s.substr(2, 4) << s.size() << "\n";
}

What will this code print?

Exercise

Count the vowels (a e i o u) in "programming is fun" and print the count.

Expected output: 5

C++

#include <iostream>
#include <string>

int main() {
    std::string text = "programming is fun";
    int vowels = 0;
    
    std::cout << vowels << "\n";
    return 0;
}

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