List or Set Iteration for Loops

The list or set iteration for loop iterates over all the elements in a list or set. In this syntax, variable, list_or_set, and code_block are placeholder values. The syntax is:

for (variable : list_or_set) {
    code_block
}

where variable must be of the same primitive or sObject type as list_or_set.

When executing this type of for loop, the Apex runtime engine assigns variable to each element in list_or_set and runs the code_block for each value.

For example, the following code outputs the numbers 1 - 10 to the debug log:

Integer[] myInts = new Integer[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

for (Integer i : myInts) {
    System.debug(i);
}