4.2 for Loops

Iterative statement that checks for condition
Repeatedly execute a a block of code as long as the condition is met
Condition specifies amount of times

for Loops vs. while Loops

while Loops: use when number of iterations is unknown
for Loops: use when number of iterations is known

int i = 0;
while (i < 5) {
    System.out.println(i);
    i++;
}

for (int i = 0; i < 5; i++) {
    System.out.println(i);
}

Three parts in for loop header: variable initialization, Boolean (conditional) expression, and increment/decrement statement

Question: Which part is which?

variable initialization (int i=0): sets variable before loop starts
Boolean (conditional) expression (i < 5): defines condition for loop to run, in this case, the loop continues as long as i is less than 5, so loops 5 times i 05
increment/decrement statement (i++): increases variable each time code block in the loop is executed, in this case it increases by 1
variable can be used in the code block for other various reasons besides specifying how many times the loop will repeat
Boolean (conditional) expression and increment/decrement statement together determine how many times the loop will repeat

int sum = 0;
int sum_all = 0;

for (int i = 0; i < 10; i++) {
    if (i % 2 == 0)
        sum += i;
    sum_all += i;
}

System.out.println(sum);
System.out.println(sum_all);