1. For Loop
CST200 – Week 2: For loop example
Instructor: Andreea Molnar

2. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
What happens when the program runs
}
i
0
Step 1:
int i=0; // i is initialised with 0
//this is done only once

3. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
Step 2:
}
i
0
What happens when the program runs
i<3; // this condition is verified
//i in this case is 0
//the codition becomes 0<3 which is
true, therefore it exectures the loop
statements (the statements between the
brakets {}, or if no braket the first
statement after the for

4. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
}
What happens when the program runs
Step 3:
i
//notice that i++ is ignored at this step
0
System.out.println(i);
// the program prints i
//i is 0, therefore 0 will be printed

5. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
}
What happens when the program runs
Step 4:
i
01
//the program reaches the } and it returns
to the for; it starts with the i++ part of
the for loop
i++; // i is incremented by 1
// i was 0, and it becomes as a result 1

6. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
Step 6:
}
i
1
What happens when the program runs
i<3; // this condition is verified
//i in this case is 1
//the codition becomes 0<3 which is
true, therefore it exectures the loop
statements (the statements between the
brakets {}, or if no braket the first
statement after the for

7. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
What happens when the program runs
}
i
1
Step 7:
System.out.println(i);
// the program prints i
//i is 1, therefore 1 will be printed

8. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
}
What happens when the program runs
Step 8:
i
12
//the program reaches the } and it returns
to the for; it starts with the i++ part of
the for loop
i++; // i is incremented by 1
// i was 1, and it becomes as a result 2

9. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
Step 9:
}
i
2
What happens when the program runs
i<3; // this condition is verified
//i in this case is 2
//the codition becomes 0<3 which is
true, therefore it exectures the loop
statements (the statements between the
brakets {}, or if no braket the first
statement after the for

10. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
What happens when the program runs
}
i
2
Step 10:
System.out.println(i);
// the program prints i
//i is 2, therefore 2 will be printed

11. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
}
What happens when the program runs
Step 8:
i
23
//the program reaches the } and it returns
to the for; it starts with the i++ part of
the for loop
i++; // i is incremented by 1
// i was 2, and it becomes as a result 3

12. Print the numbers from 0 to 2
for (int i=0; i<3; i++) {
System.out.println(i);
}
Step 11:
i
3
What happens when the program runs
i<3; // this condition is verified
//i in this case is 3
//the codition becomes 0<3 which is
true, therefore it exectures the loop
statements (the statements between the
brakets {}, or if no braket the first
statement after the for

13. Summary