Traditional For Loops

The traditional for loop in Apex corresponds to the traditional syntax used in Java and other languages. Its syntax is:
for (init_stmt; exit_condition; increment_stmt) {
    code_block
}
When executing this type of for loop, the Apex runtime engine performs the following steps, in order:
  1. Execute the init_stmt component of the loop. Note that multiple variables can be declared and/or initialized in this statement.
  2. Perform the exit_condition check. If true, the loop continues. If false, the loop exits.
  3. Execute the code_block.
  4. Execute the increment_stmt statement.
  5. Return to Step 2.
As an example, the following code outputs the numbers 1 - 10 into the debug log. Note that an additional initialization variable, j, is included to demonstrate the syntax:
for (Integer i = 0, j = 0; i < 10; i++) {
    System.debug(i+1);
}
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