Control Flow

IC supports most of the standard C control structures. One notable exception is the switch statement, which is not supported.

• Statements and Blocks
• If-Else
• While
• For
• Break

Statements and Blocks

A single C statement is ended by a semicolon. A series of statements may be grouped together into a block using curly braces. Inside a block, local variables may be defined.

If-Else

The if else statement is used to make decisions. The syntax is:

if (expression)
   statement-1
else
   statement-2

expression is evaluated; if it is not equal to zero (e.g., logic true), then statement-1 is executed.

The else clause is optional. If the if part of the statement did not execute, and the else is present, then statement-2 executes.

While

The syntax of a while loop is the following:

while (expression)
   statement

while begins by evaluating expression. If it is false, then statement is skipped. If it is true, then statement is evaluated. Then the expression is evaluated again, and the same check is performed. The loop exits when expression becomes zero.

One can easily create an infinite loop in C using the while statement:

while (1)
   statement

For

The syntax of a for loop is the following:

for (expr-1;expr-2;expr-3)
   statement

This is equivalent to the following construct using while:

expr-1;
while (expr-2) {
   statement
   expr-3;
}

Typically, expr-1 is an assignment, expr-2 is a relational expression, and expr-3 is an increment or decrement of some manner. For example, the following code counts from 0 to 99, printing each number along the way:

int i;
for (i= 0; i < 100; i++)
  printf("%d\n", i);

Break

Use of the break provides an early exit from a while or a for loop.