C++ examples

Print a greeting using std::cout.

std::endl flushes and starts a new line.

Concatenate strings with <<.

<< accepts ints natively.

Default precision is 6 significant digits.

char prints as the literal symbol.

bool prints as 0 or 1 by default.

\t = tab, \n = newline.

Chain << calls in one statement.

A C++ program need not print anything.

int holds a whole number.

double holds a decimal.

char is a single character.

bool is true / false.

std::string is the safe text type.

auto picks the type from the initializer.

const cannot be reassigned after init.

Declare multiple ints in one line.

(int) truncates a double.

Print the size of a type in bytes.

+ on two ints.

- works as expected.

* multiplies.

int / int truncates.

Cast to double for decimals.

% gives the remainder.

Compare two ints.

&& both must be true.

++x increments first, x++ returns old value first.

+= adds in place.

Run a block when a condition is true.

Two-way branch.

Multi-way branch.

Use modulus to test parity.

Cases for fixed values.

No break = fallthrough to next case.

Compact if/else expression.

if inside another if.

&& and || in one condition.

Early return on invalid input.

Print 0..4.

Decrement to count down.

Increment by 2.

Loop accumulator.

Run while a condition holds.

Body runs at least once.

break exits the loop immediately.

continue jumps to the next iteration.

Iterate over an array directly.

Multiplication table 1×3.

void function with no return.

Returns the sum.

Use a default if caller omits it.

Same name, different parameters.

Function gets a copy.

& gives the function the original.

Read-only reference, avoids copy.

Function calls itself.

An anonymous function.

Return as soon as you know the answer.

Fixed-size array of 5 ints.

Loop and accumulate.

Track max while iterating.

Iterate from end to start.

Dynamic-size array.

Range-for over a vector.

std::sort for ascending order.

std::find returns iterator.

v.erase removes one element.

Nested loops over rows×cols.

.size() / .length() return char count.

+ joins two strings.

substr(start, len).

find returns position or std::string::npos.

replace(start, len, new).

== checks character-by-character equality.

Range-for over a string.

std::toupper from <cctype>.

std::reverse from <algorithm>.

std::stoi parses an int.

& gets address, * dereferences.

*p = ... writes to the pointee.

C++11 null pointer literal.

& in declaration creates an alias.

* const → pointer cannot be re-pointed.

const int* → cannot modify pointee.

Increment moves to the next element.

Owns a heap object, frees automatically.

Reference-counted ownership.

Avoid copying with const T&.

class with public field and method.

Initialise on construction.

No-arg ctor lets you write `T t;`.

private data + public getter/setter.

Derived class reuses base behaviour.

virtual + override for runtime dispatch.

Base pointer + virtual = run derived method.

Shared across all instances.

Define + on a custom type.

~ClassName runs when the object is destroyed.