Standard Library

Vector Basics

std::vector stores a growable sequence of values.

vector A vector keeps values in order and can grow when you add another element.

Vector Basics

extraScore
vector_basics.cpp
Replay: real traced execution (multi-file project)
#include <iostream>
#include <vector>

int main() {
    int extraScore = 15;

    std::vector<int> scores{10, 20};
    scores.push_back(extraScore);

    int total = 0;
    for (int score : scores) {
        total += score;
    }

    std::cout << "count=" << scores.size() << std::endl;
    std::cout << "last=" << scores.back() << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

#include <iostream>
#include <vector>

int main() {
    int extraScore = 5;

    std::vector<int> scores{10, 20};
    scores.push_back(extraScore);

    int total = 0;
    for (int score : scores) {
        total += score;
    }

    std::cout << "count=" << scores.size() << std::endl;
    std::cout << "last=" << scores.back() << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

#include <iostream>
#include <vector>

int main() {
    int extraScore = 25;

    std::vector<int> scores{10, 20};
    scores.push_back(extraScore);

    int total = 0;
    for (int score : scores) {
        total += score;
    }

    std::cout << "count=" << scores.size() << std::endl;
    std::cout << "last=" << scores.back() << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

  1. extraScore ← 15, scores ← [10, 20], total ← 0

    4int main() {5    int extraScore→ 15 = 15; //@extraScore=5, 2567    std::vector<int> scores→ [10, 20]{10, 20};8    scores→ [10, 20, 15].push_back(extraScore15);910    int total→ 0 = 0;11    for (int score : scores) {

  2. total ← 10

    pass 1 of 3
    10int total = 0;11for (int score10 : scores[10, 20, 15]) {12    total→ 10 += score10;13}
    All 3 passes — pass 1 is the card above
    passscoretotal
    1100 → 10
    22010 → 30
    31530 → 45

  3. std::cout << "count=" << scores.size() << std::endl;

    15    std::cout << "count=" << scores[10, 20, 15].size() << std::endl;16    std::cout << "last=" << scores[10, 20, 15].back() << std::endl;17    std::cout << "total=" << total45 << std::endl;18    return 0;19}
    outputcount=3
last=15
total=45

  1. extraScore ← 5, scores ← [10, 20], total ← 0

    4int main() {5    int extraScore→ 5 = 5;67    std::vector<int> scores→ [10, 20]{10, 20};8    scores→ [10, 20, 5].push_back(extraScore5);910    int total→ 0 = 0;11    for (int score : scores) {

  2. total ← 10

    pass 1 of 3
    10int total = 0;11for (int score10 : scores[10, 20, 5]) {12    total→ 10 += score10;13}
    All 3 passes — pass 1 is the card above
    passscoretotal
    1100 → 10
    22010 → 30
    3530 → 35

  3. std::cout << "count=" << scores.size() << std::endl;

    15    std::cout << "count=" << scores[10, 20, 5].size() << std::endl;16    std::cout << "last=" << scores[10, 20, 5].back() << std::endl;17    std::cout << "total=" << total35 << std::endl;18    return 0;19}
    outputcount=3
last=5
total=35

  1. extraScore ← 25, scores ← [10, 20], total ← 0

    4int main() {5    int extraScore→ 25 = 25;67    std::vector<int> scores→ [10, 20]{10, 20};8    scores→ [10, 20, 25].push_back(extraScore25);910    int total→ 0 = 0;11    for (int score : scores) {

  2. total ← 10

    pass 1 of 3
    10int total = 0;11for (int score10 : scores[10, 20, 25]) {12    total→ 10 += score10;13}
    All 3 passes — pass 1 is the card above
    passscoretotal
    1100 → 10
    22010 → 30
    32530 → 55

  3. std::cout << "count=" << scores.size() << std::endl;

    15    std::cout << "count=" << scores[10, 20, 25].size() << std::endl;16    std::cout << "last=" << scores[10, 20, 25].back() << std::endl;17    std::cout << "total=" << total55 << std::endl;18    return 0;19}
    outputcount=3
last=25
total=55