C++ Output

cout (pronounced "see-out") is the standard output stream in C++. It lives in <iostream> and writes text to the terminal/console.

cpp Run in compiler
#include <iostream>
using namespace std;

int main() {
    cout << "Hello, Codekilla!";
    return 0;
}

Output: Hello, Codekilla!

Pour data into the stream with <<. You can chain multiple values:

cpp
int age = 21;
cout << "Age: " << age << " years";   // Age: 21 years

cpp
cout << "line1" << endl;
cout << "line2\n";

Three idiomatic forms:

cpp
cout << "line 1\n";
cout << "line 2\n";
cout << "line 3\n";

// Or chain with multiple <<:
cout << "line 1\n" << "line 2\n" << "line 3\n";

// Or a raw string literal (C++11):
cout << R"(line 1
line 2
line 3
)";

cpp
#include <iomanip>
double pi = 3.141592653589;
cout << fixed << setprecision(2) << pi;   // 3.14
cout << setw(10) << "Name";               // right-padded to 10 chars
cout << setfill('0') << setw(5) << 42;    // 00042

• Forgetting #include <iostream> — cout won't be recognised.
• Skipping using namespace std; without prefixing — std::cout instead, or both.
• endl in tight loops — flushes every line, slow for >10k iterations. Use "\n".
• Mixing printf and cout — sync the streams or use one consistently.
• Forgetting ; — every statement ends with semicolon.

1. Profile — Print your name, age, and city on three lines. Hint: 3 cout lines.
2. Format a price — Print $99.95 with exactly 2 decimal places using <iomanip>. Hint: fixed << setprecision(2).
3. Aligned table — Print 3 rows with setw(10) to left-pad names. Hint: setw from iomanip.
4. Raw string — Print a 5-line ASCII banner using a R"(...)" literal. Hint: no escaping needed.

💡 Think Like a Programmer: Print early, print often. When debugging, cout << "checkpoint A: x=" << x << "\n"; saves hours. Add it, run it, delete it.