C++ Number Pattern Programs

Q: Why do 10 and 11 run together in a C++ pattern?

cout << 10 prints the characters 1 and 0 and stays on the line. The next insertion starts immediately, so cout << 10 << 11 becomes 1011. Stream a space, or set a field width with setw, when values can be more than one digit.

Q: What is the difference between cout << n and cout << '\n'?

cout << n prints the int and stays on the same line. cout << '\n' ends the row. Call it once after the inner loop. cout << endl also ends the row and flushes the stream.

Q: How do I line up two-digit numbers in C++?

Include and call setw(2) before the number. setw applies only to the next insertion, so cout << setw(2) << n << ' ' pads n to two columns and then prints a separating space. The width does not stick for the space.

Q: Can I print a single digit as a char?

Yes, when the value is 0 through 9. cout ('0' + n) writes one character. cout << n still works, and it is the insertion you need once the value reaches 10.

Beginner

6 min read

Updated: Nov 2026

3 examples

int + cout

C++ number pattern programs printed with int and cout

Definition

Definition and Usage

A C++ number pattern is a console program that prints integers in rows. The outer for loop chooses the row. The inner for loop prints each int with cout << n, then cout << '\n' ends that row.

cout << n prints the decimal digits and stays on the line. Single digits sit next to each other (123). Once a value reaches 10, stream a space or set a width with setw so 10 and 11 do not become 1011.

The loop variable is the number.

Print col for 1, 2, 3… Print row to repeat the same digit. A separate int value that you increment is how running sequences cross from one row to the next.

Syntax

C++ Syntax

Count the outer loop down when the first row should be the longest. The inner loop still walks 1 through the current width.

C++

#include <iostream>
using namespace std;

for (int row = rows; row >= 1; row--) {
    for (int n = 1; n <= row; n++)
        cout << n;     // digits, no space
    cout << '\n';    // end the row
}

Reference

How C++ Prints a Number

Map each part of the console shape to a C++ type or stream insertion.

Piece	C++	What it does
Digit	`cout << n`	Prints the `int` with no extra space
Same digit	`cout << row`	Repeats the row number on that line
Next value	`value++`	Keeps counting across columns and rows
New row	`cout << '\n'`	Finish the row
Width	`cout << setw(2) << n`	Two columns on the next insertion only
Odd or even	`n % 2`	0/1 patterns from the remainder
One digit	`static_cast<char>('0' + n)`	One character for 0–9

Code

C++ Examples

Three programs. Each one changes only the C++ that chooses the int or its width.

Example 1 — Shrink the row with the outer loop

Start row at 5 and stop at 1. The inner loop prints 1 through row.

C++

#include <iostream>
using namespace std;

int main() {
    int rows = 5;

    for (int row = rows; row >= 1; row--) {
        for (int n = 1; n <= row; n++)
            cout << n;
        cout << '\n';
    }
    return 0;
}

How It Works

row-- makes each later line one digit shorter.
The inner for always restarts at 1, so every row begins with 1.
cout << n prints the int; cout << '\n' ends the row.

Example 2 — Print the row number, not the column

The inner loop only decides how many times to print. The value is row.

C++

#include <iostream>
using namespace std;

int main() {
    int rows = 5;

    for (int row = 1; row <= rows; row++) {
        for (int col = 1; col <= row; col++)
            cout << row;
        cout << '\n';
    }
    return 0;
}

How It Works

Row 1 runs the inner loop once and prints 1.
Row 3 runs it three times and prints 3 each time.
Swap cout << row for cout << col and the line becomes 123.

Example 3 — Keep two-digit values aligned

setw(2) reserves two columns for the next insertion. The following ' ' separates columns.

C++

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int value = 1;

    for (int row = 1; row <= 4; row++) {
        for (int col = 1; col <= row; col++) {
            cout << setw(2) << value << ' ';
            value++;
        }
        cout << '\n';
    }
    return 0;
}

How It Works

value lives outside both loops, so counting continues on the next row.
setw(2) applies only to value, so 1 is two columns and 10 stays two digits.
The ' ' after value is a separate insertion, so the width does not pad the space.

Programs

62 C++ Number Pattern Programs

Each card is a full C++ program: nested for loops, an int for the cell, and cout << n. Open one for the walkthrough.

C++ Number Pattern Programs

Definition and Usage

C++ Syntax

How C++ Prints a Number

C++ Examples

Example 1 — Shrink the row with the outer loop

How It Works

Example 2 — Print the row number, not the column

How It Works

Example 3 — Keep two-digit values aligned

How It Works

62 C++ Number Pattern Programs

Frequently Asked Questions

Related C++ Topics

Number Pattern 1

Star Patterns

Alphabet Patterns

C++ Strings

Next: Number Pattern 1

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