For Loop


title: For Loop

For Loop

The for loop executes a block of code repeatedly until a specified conditional expression evaluates to false.

Anatomy of for loop:

for (initialization; condition; iterator) { body }
  • initialization – The initialization statement(s) sets the initial condition and run only once before you enter the body of the loop.
  • condition – Boolean expression which determines whether the body of the loop should execute again or the loop should exit.
  • iterator – Executes after each iteration of the body of the loop.

Example 1

for (int i = 0; i < 5; i++) { Console.WriteLine("Number " + i); }

Output:

> Number 0 > Number 1 > Number 2 > Number 3 > Number 4
  • Only counts to 4 due to the fact that the initial number is 0 meaning that 5 numbers including 0 would reach 4.

Example 2

int j = 0; for (int i = 0; j < 5; i++) { Console.WriteLine("Numbers {0} {1}", i, j); j++; }

Output:

> Numbers 0 0 > Numbers 1 1 > Numbers 2 2 > Numbers 3 3 > Numbers 4 4

Example 3 – Simplification of Example 2

for (int i = 0, j = 0; i < 5 && j < 5; i++, j++) { Console.WriteLine("Numbers {0} {1}", i, j); }

Output:

> Numbers 0 0 > Numbers 1 1 > Numbers 2 2 > Numbers 3 3 > Numbers 4 4

Example 4

for (int i = 5; i > 0; i--) { Console.WriteLine("Number " + i); }

Output:

> Number 5 > Number 4 > Number 3 > Number 2 > Number 1

Example 5

// Infinite loop - The loop body is executed infinitely for (; ;) { Console.WriteLine("The universe is infinite"); } // Anything after infinite loop is reported as "Unreachable code detected" in Visual Studio Console.WriteLine("Never considered for execution");

Output:

> The universe is infinite > The universe is infinite > The universe is infinite > .... > ....

Example 6

int i = 0; for (; i < 5;) { Console.WriteLine("Number " + i); i++; }

Output:

> Number 0 > Number 1 > Number 2 > Number 3 > Number 4

Other Resources

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