for

Like while and do/while, the for statement is used to create an execution loop. A loop usually contains an initialization expression that sets the initial value of a counter, an expression that tests the counter value, and an incrementing expression that alters the counter. Using while, the initialization and incrementing expressions are not part of the basic statement syntax. Instead, they are separate statements. The for statement simply integrates these additional statements into a single composite statement. For has the format

for( initialize; test; increment )
  statement

This is identical to the while statement

initialize ;
while( test ) {
  statement
  increment ;
}

For example, code that sums the square of all integers between 1 and 10 can be created using for as follows:

var total=0,n;
for(n=1; n<=10; n++)
total+=n*n;

The for statement does not provide any functionality that you cannot accomplish using while; it just allows you to create code that is a bit more structured. For this reason, for is the statement you will use most often to create program loops.

See Also

Loop Primitives