Source code

Object code

Language reference

A program consists of a single function definition.

A function definition looks like this:

int functionName (int varName, int varName, ...) {
    functionBody
}

or

void functionName (int varName, int varName, ...) {
    functionBody
}

It has a return type (which must be either int or void), a name (any name of your choosing), and a list of zero or more parameters, separated by commas and enclosed in parentheses. Each parameter has a type (which must be int) followed by a parameter name (of your choosing). The function body is enclosed with braces.

A function body is a list of zero or more local variable declarations followed by a list of zero or more statements.

A local variable declaration looks like this:

int varName = constant;

It has a type (which must be int), a variable name (of your choosing), an equals sign, an integer constant, and a semicolon.

There are five kinds of statements:

• An assignment statement looks like this:

  varName = exp;

  It has a variable name (which must have been previously declared as a parameter or local variable), an equals sign, an integer-valued expression, and a semicolon.

• A return statement looks like this:

  return exp;

  It has the keyword 'return', an integer-valued expression, and a semicolon. A return statement may appear in a function only if the function's return type is int.

• A conditional statement looks like this:

  if (exp) {
      statements
  }
  else {
      statements
  }

  It consists of the keyword 'if', a boolean-valued expression enclosed in parentheses, a list of zero or more statements enclosed in braces, the keyword ``else'', and a list of zero or more statements enclosed in braces. The else part is optional, however.

• A while statement looks like this:

  while (exp) {
    statements
  }

  It consists of the keyword 'while', a boolean-valued expression enclosed in parentheses, and a list of zero or more statements enclosed in braces.

There are many kinds of exps:

• A previously-declared variable is an integer-valued expression.
• An integer constant is an integer-valued expression.
• Compound expressions of the form
  • exp + exp
  • exp - exp
  • -exp are integer-valued expressions.
• Compound expressions of the form
  • exp > exp
  • exp < exp
  • exp >= exp
  • exp <= exp
  • exp == exp
  • exp != exp are boolean-valued expressions.

Sample Programs

This function returns the sum of its two parameters.

int add (int a, int b) {
    return a+b;
}

This function returns the larger of its two parameters.

int largest (int a, int b) {
    if (a > b) {
        return a;
    } else {
        return b;
    }
}

This function orders the three parameters into ascending order.

void sort (int a, int b, int c) {
    int temp = 0;
    if (a > b) {
        temp = a;
        a = b;
        b = temp;
    }
    if (b > c) {
        temp = b;
        b = c;
        c = temp;
    }
    if (a > b) {
        temp = a;
        a = b;
        b = temp;
    }
}