Multiply

The multiply operator is an asterisk. It computes the product of 2 numbers. Multiplication is a standard operation: C# is the same as other languages.

This operator obeys the operator precedence rules. So we can mix additions and multiplications and multiplication will come first.

Example

We compute the product of 2 operands using the multiplication operator. You can multiply any 2 numbers that can be implicitly converted to compatible types.

Info The C# language specification defines many predefined arguments (int, double) for the multiplication operator.

Here We compute the product of 100 and 5. The number 100 is a constant. The value 5 was determined at program runtime.

Note Because one value was not known at compile-time, the C# compiler cannot compute the product of the operands statically.

using System;

// Use a constant local and a dynamically
// ... determined integer as operands.
const int operand1 = 100;
int operand2 = int.Parse("5");

// Compute the product and store it in a local variable.
int product = operand1 * operand2;
Console.WriteLine(product);

// You can check the value of a multiple expression in an if-statement.
if ((operand1 * operand2) == 500)
{
    Console.WriteLine("Is equal");
}
// You can multiply a number against itself.
operand2 *= 2;
Console.WriteLine(operand2); // Now equal to 10 not 5.500
Is equal
10

Table

Next we write a multiplication table program. It uses two nested for-loops. The numbers we loop over are in the range 1 to 9.

Info In the innermost statement, we use the multiplication operator and then use a ToString format pattern.

Also A newline is printed at the end of each nine numbers in the loop. This improves the output format.

using System;

// Loop through all operands in the multiplication table.
for (int a = 1; a < 10; a++)
{
    for (int b = 1; b < 10; b++)
    {
        // Write the multiplied number.
        Console.Write((a * b).ToString("00 "));
    }
    // New line.
    Console.WriteLine();
}01 02 03 04 05 06 07 08 09
02 04 06 08 10 12 14 16 18
03 06 09 12 15 18 21 24 27
04 08 12 16 20 24 28 32 36
05 10 15 20 25 30 35 40 45
06 12 18 24 30 36 42 48 54
07 14 21 28 35 42 49 56 63
08 16 24 32 40 48 56 64 72
09 18 27 36 45 54 63 72 81

Operator precedence

The multiplication operator has a greater precedence than plus or minus. The rules for operator precedence in the C# language are the same as those for arithmetic.

Tip The C# language has additional rules for coding-specific operators not found in regular mathematics.

We looked at multiplying numbers. The multiplication operator is the star character. The compound operator is represented by the "*=" characters.