For loop in Java

The for statement provides a compact way to iterate over a range of values. Programmers often refer to it as the “for loop” because of the way in which it repeatedly loops until a particular condition is satisfied.

The general form of the for statement can be expressed as follows:

for (initialization; termination; increment) {
    statement(s);
}

Here :

1. The initialization expression initializes the loop; it’s executed once, as the loop begins.
2. When the termination expression evaluates to false, the loop terminates.
3. The increment expression is invoked after each iteration through the loop; it is perfectly acceptable for this expression to increment or decrement a value.

For example, the following for-loop statement will print all integers between 1 and 10, inclusive:

for(int num = 1; num <= 10; num++){
	 System.out.println(num);
}

The execution flows like this:

1. First, int num = 1 is executed, which declares an int variable num and initializes it to 1.
2. Then, condition-expression (num <= 10) is evaluated, which is 1 <= 10. It evaluates to true for the first time. Now, the statement associated with the for-loop statement is executed, which prints the current value of num.
3. Finally num++ is executed, which increments the value of num by 1. At this point, the value of num becomes 2.
4. The condition-expression 2 <= 10 is evaluated, which returns true, and again current value of num is printed.
5. This process continues until the value of num becomes 10 and it is printed.
6. After that, num++ sets the value of num to 11, and the expression 11 <= 10 returns false, which stops the execution of the for-loop statement.

Please note that initialization and increment are optional parts, can be controlled from other places. But termination condition is mandatory for a finite loop. If you do not mention termination condition, then it will be an infinite loop.

int num = 1;
for( ; num <= 10 ; ){
	 System.out.println(num);
	 num++;
}

Above for loop is perfectly valid and will result in similar output as it’s previous version.

In Next post, we will learn about another version of for loop i.e. enhanced for loop.

Happy Learning !!