Ce este C++?
C++ este un limbaj compilat, multi-paradigmă, folosit pentru aplicații performante (sisteme, jocuri, embedded). În continuare găsești o sinteză practică cu accent pe bibliotecile <iostream> și <cmath>.
What is C++?
C++ is a compiled, multi-paradigm language for high-performance apps (systems, games, embedded). Below is a practical tour focused on <iostream> and <cmath>.
Intrare / Ieșire cu <iostream>
Fluxuri standard:
std::cin (input), std::cout (output), std::cerr (erori), std::clog (log).#include <iostream> // std::cout, std::cin, std::endl
#include <string>
int main() {
std::string nume;
int varsta = 0;
std::cout << "Nume: ";
std::getline(std::cin, nume);
std::cout << "Vârsta: ";
if (!(std::cin >> varsta)) {
std::cerr << "Input invalid!\n";
return 1;
}
std::cout << "Salut, " << nume << " (" << varsta << " ani)\n";
std::clog << "[INFO] Date afișate cu succes.\n";
}
Formatare simplă (endl, \n, concatenare)
#include <iostream>
int main() {
std::cout << "Linia 1" << std::endl; // goliți bufferul și newline
std::cout << "Linia 2\n"; // doar newline (mai rapid)
}
Input / Output with <iostream>
Standard streams:
std::cin (input), std::cout (output), std::cerr (errors), std::clog (logs).#include <iostream>
#include <string>
int main() {
std::string name;
int age = 0;
std::cout << "Name: ";
std::getline(std::cin, name);
std::cout << "Age: ";
if (!(std::cin >> age)) {
std::cerr << "Invalid input!\n";
return 1;
}
std::cout << "Hello, " << name << " (" << age << ")\n";
std::clog << "[INFO] Output successful.\n";
}
Simple formatting (endl, \n, chaining)
#include <iostream>
int main() {
std::cout << "Line 1" << std::endl; // flush + newline
std::cout << "Line 2\n"; // just newline (faster)
}
Operații matematice cu <cmath>
Funcții uzuale:
std::sqrt, std::pow, std::hypot, std::sin, std::cos, std::tan, std::ceil, std::floor, std::round, std::fabs.#include <iostream>
#include <cmath> // sqrt, pow, sin, cos, etc.
int main() {
double a = 3.0, b = 4.0;
double c = std::hypot(a, b); // radical(a^2 + b^2)
double aria_cerc = M_PI * std::pow(5.0, 2); // πr^2 (M_PI e disponibil pe majoritatea platformelor)
double s = std::sin(M_PI/6.0); // sin(30°) = 0.5
double c0 = std::cos(M_PI/3.0); // cos(60°) = 0.5
std::cout << "Cateta a=" << a << ", b=" << b
<< ", ipotenuza=" << c << '\n';
std::cout << "Aria cerc r=5 este " << aria_cerc << '\n';
std::cout << "sin(30°)=" << s << ", cos(60°)=" << c0 << '\n';
// Rotunjiri:
std::cout << "ceil(2.3)=" << std::ceil(2.3) << ", floor(2.7)=" << std::floor(2.7)
<< ", round(2.5)=" << std::round(2.5) << '\n';
}
Exemplu: ecuație de gradul II
#include <iostream>
#include <cmath>
int main() {
double a, b, c;
std::cout << "ax^2 + bx + c = 0\nA=";
std::cin >> a; std::cout << "B="; std::cin >> b; std::cout << "C="; std::cin >> c;
double delta = b*b - 4*a*c;
if (delta < 0) {
std::cout << "Fără soluții reale.\n";
} else {
double r1 = (-b - std::sqrt(delta)) / (2*a);
double r2 = (-b + std::sqrt(delta)) / (2*a);
std::cout << "Rădăcini: " << r1 << " și " << r2 << '\n';
}
}
Math operations with <cmath>
Usual functions:
std::sqrt, std::pow, std::hypot, std::sin, std::cos, std::tan, std::ceil, std::floor, std::round, std::fabs.#include <iostream>
#include <cmath>
int main() {
double a = 3.0, b = 4.0;
double c = std::hypot(a, b); // sqrt(a^2 + b^2)
double circle = M_PI * std::pow(5.0, 2);
double s = std::sin(M_PI/6.0); // 0.5
double c0 = std::cos(M_PI/3.0); // 0.5
std::cout << "a=" << a << ", b=" << b << ", hyp=" << c << '\n';
std::cout << "Area r=5: " << circle << '\n';
std::cout << "sin(30°)=" << s << ", cos(60°)=" << c0 << '\n';
std::cout << "ceil(2.3)=" << std::ceil(2.3)
<< ", floor(2.7)=" << std::floor(2.7)
<< ", round(2.5)=" << std::round(2.5) << '\n';
}
Example: quadratic equation
#include <iostream>
#include <cmath>
int main() {
double a, b, c;
std::cout << "ax^2 + bx + c = 0\nA=";
std::cin >> a; std::cout << "B="; std::cin >> b; std::cout << "C="; std::cin >> c;
double d = b*b - 4*a*c;
if (d < 0) {
std::cout << "No real roots.\n";
} else {
double r1 = (-b - std::sqrt(d)) / (2*a);
double r2 = (-b + std::sqrt(d)) / (2*a);
std::cout << "Roots: " << r1 << " and " << r2 << '\n';
}
}
Structuri liniare
#include <iostream>
#include <cmath>
int main() {
double x = 2.0;
double y = std::sqrt(x) + std::pow(x, 3); // calcule în linie
std::cout << "Rezultat: " << y << '\n';
}
Linear structures
#include <iostream>
#include <cmath>
int main() {
double x = 2.0;
double y = std::sqrt(x) + std::pow(x, 3); // inline math
std::cout << "Result: " << y << '\n';
}
Structuri alternative
#include <iostream>
#include <cmath>
int main() {
double r; std::cin >> r;
double aria = M_PI * r * r;
if (aria > 100.0) {
std::cout << "Cerc mare\n";
} else {
std::cout << "Cerc mic\n";
}
}
Alternative structures
#include <iostream>
#include <cmath>
int main() {
double r; std::cin >> r;
double area = M_PI * r * r;
if (area > 100.0) {
std::cout << "Big circle\n";
} else {
std::cout << "Small circle\n";
}
}
Structuri repetitive
#include <iostream>
#include <cmath>
int main() {
// tablă trigonometrie simplă
for (int deg = 0; deg <= 90; deg += 30) {
double rad = deg * M_PI / 180.0;
std::cout << deg << "°: sin=" << std::sin(rad)
<< ", cos=" << std::cos(rad) << '\n';
}
}
Loop structures
#include <iostream>
#include <cmath>
int main() {
// tiny trig table
for (int deg = 0; deg <= 90; deg += 30) {
double rad = deg * M_PI / 180.0;
std::cout << deg << "°: sin=" << std::sin(rad)
<< ", cos=" << std::cos(rad) << '\n';
}
}
Test C++ (6 întrebări)
Întrebări despre <iostream> și <cmath>.
C++ Quiz (6 questions)
Questions about <iostream> and <cmath>.