Transforming and Accumulating: std::transform, std::accumulate, std::count_if0%

Lambda Expressions: Syntax, Capture Clauses ([=], [&]), and Predicates

Transforming and Accumulating: std::transform, std::accumulate, std::count_if

Intermediate13 min read•Updated: 2026-10-22

🧪 Transforming and Accumulating: std::transform and std::accumulate

Introduction

Modern C++ encourages declarative programming. Rather than writing manual for loops with accumulator variables, STL algorithms from <algorithm> and <numeric> perform batch transformations clearly and safely.

➕ Computing Aggregates with `std::accumulate` (`<numeric>`)

1#include <iostream>
2#include <vector>
3#include <numeric>
4 
5int main() {
6    std::vector<double> feesCollected = {2999.0, 3499.0, 4999.0, 3499.0};
7 
8    // Syntax: std::accumulate(start, end, initial_sum)
9    double totalRevenue = std::accumulate(feesCollected.begin(), feesCollected.end(), 0.0);
10 
11    std::cout << "Total Revenue Collected: ₹" << totalRevenue << "\n";
12    std::cout << "Average Revenue: ₹" << (totalRevenue / feesCollected.size()) << "\n";
13 
14    return 0;
15}

🔀 Mapping Data with `std::transform`

std::transform applies an operation to every element, writing the output to a destination:

1#include <iostream>
2#include <vector>
3#include <algorithm>
4 
5int main() {
6    std::vector<int> rawMarks = {45, 52, 60, 75};
7    std::vector<int> curvedMarks(rawMarks.size());
8 
9    // Add 5 grace marks to each student:
10    std::transform(rawMarks.begin(), rawMarks.end(), curvedMarks.begin(), [](int score) {
11        return score + 5;
12    });
13 
14    std::cout << "Curved Scores: ";
15    for (int score : curvedMarks) std::cout << score << " ";
16    std::cout << "\n";
17 
18    // Count how many passed (score >= 50):
19    int passCount = std::count_if(curvedMarks.begin(), curvedMarks.end(), [](int s) {
20        return s >= 50;
21    });
22    std::cout << "Total Passed: " << passCount << "/" << curvedMarks.size() << "\n";
23 
24    return 0;
25}

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Sorting and Searching: std::sort, std::stable_sort, std::binary_search	Lambda Expressions: Syntax, Capture Clauses ([=], [&]), and Predicates

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Lambda Expressions: Syntax, Capture Clauses ([=], [&]), and Predicates

Transforming and Accumulating: std::transform, std::accumulate, std::count_if

Intermediate13 min read•Updated: 2026-10-22

Study Materials

🧪 Transforming and Accumulating: std::transform and std::accumulate

Introduction

➕ Computing Aggregates with `std::accumulate` (`<numeric>`)

1#include <iostream>
2#include <vector>
3#include <numeric>
4 
5int main() {
6    std::vector<double> feesCollected = {2999.0, 3499.0, 4999.0, 3499.0};
7 
8    // Syntax: std::accumulate(start, end, initial_sum)
9    double totalRevenue = std::accumulate(feesCollected.begin(), feesCollected.end(), 0.0);
10 
11    std::cout << "Total Revenue Collected: ₹" << totalRevenue << "\n";
12    std::cout << "Average Revenue: ₹" << (totalRevenue / feesCollected.size()) << "\n";
13 
14    return 0;
15}

🔀 Mapping Data with `std::transform`

std::transform applies an operation to every element, writing the output to a destination:

1#include <iostream>
2#include <vector>
3#include <algorithm>
4 
5int main() {
6    std::vector<int> rawMarks = {45, 52, 60, 75};
7    std::vector<int> curvedMarks(rawMarks.size());
8 
9    // Add 5 grace marks to each student:
10    std::transform(rawMarks.begin(), rawMarks.end(), curvedMarks.begin(), [](int score) {
11        return score + 5;
12    });
13 
14    std::cout << "Curved Scores: ";
15    for (int score : curvedMarks) std::cout << score << " ";
16    std::cout << "\n";
17 
18    // Count how many passed (score >= 50):
19    int passCount = std::count_if(curvedMarks.begin(), curvedMarks.end(), [](int s) {
20        return s >= 50;
21    });
22    std::cout << "Total Passed: " << passCount << "/" << curvedMarks.size() << "\n";
23 
24    return 0;
25}

Next Lesson

Lambda Expressions: Syntax, Capture Clauses ([=], [&]), and Predicates

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Sorting and Searching: std::sort, std::stable_sort, std::binary_search	Lambda Expressions: Syntax, Capture Clauses ([=], [&]), and Predicates

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next

🧪 Transforming and Accumulating: std::transform and std::accumulate

Introduction

➕ Computing Aggregates with std::accumulate (<numeric>)

🔀 Mapping Data with std::transform

Lambda Expressions: Syntax, Capture Clauses ([=], [&]), and Predicates

Related Lessons

Practice Quiz

Loading Page Content...

🧪 Transforming and Accumulating: std::transform and std::accumulate

Introduction

➕ Computing Aggregates with std::accumulate (<numeric>)

🔀 Mapping Data with std::transform

Lambda Expressions: Syntax, Capture Clauses ([=], [&]), and Predicates

Related Lessons

Practice Quiz

➕ Computing Aggregates with `std::accumulate` (`<numeric>`)

🔀 Mapping Data with `std::transform`

➕ Computing Aggregates with `std::accumulate` (`<numeric>`)

🔀 Mapping Data with `std::transform`