coldmud.info: Looping Statements

Looping Statements

C-- provides three kinds of looping statements. These statements allow you to traverse a list or a range of numbers, or to execute a statement as long as a certain condition is true. C-- also provides two kinds of jump statements which allow you to prematurely exit from a loop or continue onto the next iteration.

The for-list statement allows you to traverse a list. It has the following syntax:

for variable in (list)
    statement

variable must be the name of a local variable, and list must be an expression of list type. The interpreter executes statement once for each element of list. variable contains the list element that the interpreter is at. Here is an example of a method using a for-list statement:

var a, s;
a = ["foo", "bar", "baz"];
for s in (a)
    .tell(s);

You can also iterate over the associations in a dictionary with the for-list statement; see Dictionaries.

The for-range statement allows you to traverse a range of integers. It has the following syntax:

for variable in [lower .. upper]
    statement

As before, variable must be the name of a local variable. lower and upper must be expressions of integer type. The interpreter executes statement once for each number from lower to upper inclusive. variable contains the number that the interpreter is at. Assigning to variable within the loop body will not change the status of the loop; the interpreter remembers what number it is at independently of the loop index. Here is an example of a method using a for-range statement:

var i;
for i in [1 .. 10]
    .tell(tostr(i));

The while statement allows you to execute code as long as a condition expression is true. The while statement has the following syntax:

while (expression)
    statement

The interpreter continually evaluates expression and executes statement until the value of expression is false, according to the rules in Data Types. Here is an example of a method using a while statement:

var a;
a = 1;
while (a < 35)
    a = a * 2;
.tell(tostr(a));

The break statement allows you to exit a loop prematurely. The break statement has the following syntax:

break;

The interpreter jumps to the end of the innermost for-list, for-range, or while statement.

The continue statement allows you to jump to the next iteration of a loop. The continue statement has the following syntax:

continue;

The interpreter skips the remainder of the loop body and begins another iteration of the innermost for-list, for-range, or while statement.

The break and continue statements do not allow you to break out of two loops at once. C-- does not provide any general jump mechanism. If you find that you require jumps other than break or continue statements, then you probably need to reorganize your code.