For loops

Syntax#

• for(init; condition; increment){ content_code(); } // general syntax
• for(int i = 0; i < numberRuns; ++i){ actions_with(i); } // run an action for a numberRuns times
• for(int i = 0; i < sizeof(array); ++i){ actions_with(array[i]); } // iteration over an array

General for loop

Most programming languages support the for-loop control structure.

It is generally implemented in this way:

for(init; condition; increment){
    content_code();
}

The above pseudocode is identical with the pseudocode below:

init;
start_loop:
if(condition){
    content_code();
    increment;
    goto start_loop;
}

This shows that:

• init is run before the loop, used to initialize things for running that loop
  • In some programming languages like Java, variables can be declared in init, and the scope of the declared variables will be limited to that loop.
• condition is a condition to determine when the loop can be run. If this evaluates to false, the loop will stop executing.
• increment is usually a statement used to manipulate parameters used in condition, so when increment is run a certain number of times, condition becomes false and the loop breaks.
• content_code() is the core code to be run within the loop.