For Loop Part 1
Part of the Fundamentals section of Coddy's Java journey — lesson 42 of 73.
Sometimes when programming, it's necessary to perform the same or almost the same operation a couple of times.
To prevent writing the same thing over and over again, we can use Loops.
The for loop has the following syntax:
for (initialization; condition; update) {
code
}The initialization, condition and update determine what is the start value and what is the end value.
For example, loop from 0 to 5 (not including):
for (int i = 0; i < 5; i++) {
System.out.println(i);
}It will execute the print statement 5 times:
0
1
2
3
4Loops have many use cases. For example, let's sum all the numbers from 1 to 100:
int sum_numbers = 0;
for (int i = 1; i <= 100; i++) {
sum_numbers += i;
}
System.out.println(sum_numbers);This will first loop through all numbers between 1 and 100 (including 100 because of <= sign) and sum all of them, then it will print the sum_numbers variable
Challenge
BeginnerWrite a program that prints "Hello Coddy: " and the i value from 3 to 27 (including, which means printing the numbers 3, 4, 5, ..., 26, 27, making it 27 - 3 + 1 = 25 times in total), do it using a for loop.
It will look like this:
Hello Coddy: 3
Hello Coddy: 4
...
Hello Coddy: 27Cheat sheet
The for loop allows you to repeat code multiple times with the following syntax:
for (initialization; condition; update) {
code
}Example - loop from 0 to 5 (not including):
for (int i = 0; i < 5; i++) {
System.out.println(i);
}This outputs:
0
1
2
3
4Example - sum numbers from 1 to 100:
int sum_numbers = 0;
for (int i = 1; i <= 100; i++) {
sum_numbers += i;
}
System.out.println(sum_numbers);Try it yourself
class Main {
public static void main(String[] args) {
// Write code here
}
}
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Fundamentals
4Operators Part 1
Arithmetic OperatorsModulo OperatorIncrement/DecrementPost Increment/DecrementArithmetic ShortcutsComparison OperatorsString Comparison5Operators Part 2
Logical Operators Part 1Logical Operators Part 2Recap - Simple LogicLogical Operators Part 3Logical Operators Part 4
3Variables Part 2
ConstantsNaming ConventionsRecap - Initialize VariablesType Casting Part 1Type Casting Part 26Decision Making
If StatementIf - ElseSwitch StatementTernary OperatorRecap - If ElseNested If - Else