Processing: Iteration For

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for

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Controls a sequence of repetitions. A basic for structure has three parts: init, test, and update. Each part must be separated by a semicolon (;). The loop continues until the test evaluates to false. When a for structure is executed, the following sequence of events occurs:

1. The init statement is run.
2. The test is evaluated to be true or false.
3. If the test is true, jump to step 4. If the test is false, jump to step 6.
4. Run the statements within the block.
5. Run the update statement and jump to step 2.
6. Exit the loop.

Example
// Nested for() loops can be used to
// generate two-dimensional patterns
for (int i = 30; i < 80; i = i+5) {
for (int j = 0; j < 80; j = j+5) {
point(i, j);
}
}

Syntax
for (init; test; update) {
statements
}

for (datatype element : array) {
statements
}

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while

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Controls a sequence of repetitions. The while structure executes a series of statements continuously while the expression is true. The expression must be updated during the repetitions or the program will never "break out" of while.

This function can be dangerous because the code inside the while loop will not finish until the expression inside while becomes false. It will lock out all other code from running (e.g., mouse and keyboard events will not be updated). Be careful — if used incorrectly, this can lock up your code (and sometimes even the Processing environment itself).

Example
int i = 0;
while (i < 80) {
line(30, i, 80, i);
i = i + 5;
}

Syntax
while (expression) {
statements
}

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