6. Statements

In SCalc there are five types of statements:

Declaration
Assignment
Conditional
Loop
Print

Each statement ends with a semicolon. White space is not important in SCalc.

Assertion: Whitespace is guaranteed to be a space, a tab, a carriage return, or a new line. (simple-whitespace)

6.1. Declaration

A variable declaration in SCalc has the following form:

int <id> = <expr>;

id is the identifier of a variable.
expr is an expression.

Variables have a few properties:

cannot be used before being declared.
cannot be declared without initialisation.
cannot be declared more than once in an SCalc program.

Examples of valid declarations are:

int i = 9;
int j = 9 * 4 + 10;
int k = i * j;

Examples of invalid declarations are:

int i;
int j =;

6.2. Assignment

Variable assignment is similar to variable declaration but it allows variables to be assigned new values. An assignment in SCalc has the following form:

<id> = <expr>;

id is the identifier of an already declared variable.
expr is an expression.

6.3. Conditional

A conditional in SCalc has the following form:

if (<expr>)
  <statement-1>
  <statement-2>
  ...
  <statement-n>
fi;

expr is an expression. The body of the if statement is executed if and only if this expression evaluates to a non-zero value.
statement-* is any type of statement except a declaration. This means there can be assignments, nested loops, nested conditionals, and prints. There does not have to be any statements in the conditional.

Clarification: Declarations in conditionals can lead to undefined values due to global scoping. (no-decl-cond)

6.4. Loop

A loop in SCalc has the following form:

loop (expr)
  <statement-1>
  <statement-2>
  ...
  <statement-n>
pool;

expr is an expression. The body of the loop statement is repeatedly evaluated as long as this expression is non-zero. The expression is evaluated prior to running the body similar to a C while loop.
statement-* is any type of statement except a declaration. This means there can be assignments, nested loops, nested conditionals, and prints. There does not have to be any statements in the loop, but without side effects a loop will be infinite (unless it is never entered).

Clarification: Declarations in loops can lead to undefined or repeatedly defined values due to global scoping. (no-decl-loop)

6.5. Print

Print statements print the integer value of an expression followed by a newline. A print statement in SCalc has the following form:

print(<expr>);

expr is an expression.

For example, the input:

int i = 0;
loop (i < 5)
  print(i);
  i = i + 1;
pool;

should print: