Hi friend,


C and Pascal are both arguably descendants of the ALGOL programming language series. ALGOL introduced so-called "structured programming", where programs were constructed of single entry-single exit "components" such as "if", "while", "for", "case", etc. Also, whereas before ALGOL only the expression syntax for languages was described systematically,


In Pascal, routines that return a value are called functions, and routines that don't return a value are called procedures. In C all routines are called functions, however routines that do not return a value are declared to return "void", meaning that they do not return anything. Actually "void" is not really a valid variable type, it can only be used when declaring the return type of a function. It cannot be used for declaring normal variables of this type,



The statements used between C and Pascal are roughly analogous. if (x) ... else ... while (x) ... do ... while (x) ... switch (x) { case a: ...; case b: ...; default: } if x then ... else ... while x do ... repeat ... until x case x of a: ...; b: ... end Pascal, in its original form, did not have an equivalent version of "default" case (this is a common extension). C has so called "early out" statements "break" and "continue". Pascal does not.


Using the preceeding rules, here is an example of a C function with no return value, and its Pascal equivalent procedure.
//1

void myProc( long myFirstParam, char mySecondParam )
{
/* Here we have some code that does something */
}

Now the Pascal version:

{ 10 }

procedure myProc(myFirstParam: LONGINT, mySecondParam: CHAR);
BEGIN
(* Here we have some code that does something *)
END;

Pascal returns its function values by assigning a value to the function name. C returns a value by using its return statement. Here is an example of a C function that takes no parameters and that returns a double precision floating point value, and then its Pascal equivalent:

/* 11 */

// C version

double myFunc(void){
return 3.14;
}

{12}

function myFunc : DOUBLE; (* Pascal Version *)
BEGIN
myFunc := 3.14
END;
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Thanks