This content originally appeared on DEV Community and was authored by Eduardo Julião
Iteration statements are code blocks that executes instructions in a loop.
There a 4 types of iteration statements
- For
- Foreach
- While
- Do... While
For
The for loop keeps executing until a certain condition is met.
for(<initializer>; <condition>; <iterator>)
{
// Code to be executed
}
Initializer
Creates and initialize a variable to be used inside the for loop. This variable cannot be accessed from outside.
Condition
A boolean expression that must return either true or false. The loop will keep executing until this expression returns false.
Iterator
Defines the incremental or decremental of Initializer variable.
Example
Iterator adds a value to i each loop.
for(int i = 0; i < 10; i++)
{
Console.WriteLine("Value of i: {0}", i);
}
Iterator removes a value of i each loop.
for(int i = 10; i > 10; i--)
{
Console.WriteLine("Value of i: {0}", i);
}
Initializer can be declared outside the for loop
In this scenario, the i variable can be accessed outise the loop
int i = 0;
for(; i < 10; i++)
{
Console.WriteLine("Value of i: {0}", i);
}
Iterator can be managed inside the loop
for(int i = 0; i < 10; )
{
Console.WriteLine("Value of i: {0}", i);
i++;
}
Iterator managed insithe the loop and initializer variable declared outside the for loop
int i = 0
for(; i < 10; )
{
Console.WriteLine("Value of i: {0}", i);
i++;
}
Initializer, Condition and Iterator are managed ooutside the parenthesis
int i = 0;
for(;;)
{
if(i < 10)
{
Console.WriteLine("Value of i: {0}", i);
i++;
}
else
break; // force exit from loop
}
Working with arrays
int[] array = new [] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
for(int i = 0; i < array.Count - 1; i ++)
{
int currentItem = array[i];
Console.WriteLine("Current value of item inside array is: " + currentItem);
}
In the example above we're using the .Count property of the array to know how many items are inside it.
Since arrays index start at 0, we use remove one iteration with - 1, without it, the for looop will look for an item that does not exists in the array and trhow an error.
To better exemplify this
int[] array = new [] { 1, 2, 3 };
Console.WriteLine(array[0]); // Outputs 1
Console.WriteLine(array[1]); // Outputs 2
Console.WriteLine(array[2]); // Outputs 3
Foreach
The foreach loop iterates through each item inside a collection.
The DataType must match the type of the collection you're iterating.
foreach(<DataType> <variableName> in <collection)
{
// code
}
Example
int[] array = new [] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
foreach(int i in array)
{
Console.WriteLine("Current value of i is: " + i);
}
While
In the while loop, the code block will run until the condition returns true.
while(<condition>)
{
// Code
}
Example
Execute the instrunction until i is smaller than 1
int i = 0; // initializer
while(i < 10) // condition
{
Console.WriteLine("Value of i: " + i);
i++; // iterator
}
Using a boolean variable
int i = 0;
bool isBiggerThan10 = false;
while(isBiggerThan10)
{
Console.WriteLine("Value of i: " + i);
i++; // iterator
isBiggerThan10 = i > 10; // Checks if i is bigger than 10 and assing the result to the variable.
}
Do... While
The difference between while and do...while, is that while checks the condition before executing, and do...while always executes at least once.
do
{
// Code
} while(<condition>)
Examples
int i = 0;
do
{
Console.WriteLine("i = {0}", i);
i++;
} while (i < 10);
This content originally appeared on DEV Community and was authored by Eduardo Julião
Eduardo Julião | Sciencx (2021-07-09T16:45:37+00:00) Iteration Statements. Retrieved from https://www.scien.cx/2021/07/09/iteration-statements/
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