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articles/pascal.md
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@ -1,17 +1,17 @@
# Pascal # Pascal
Pascal is a procedural programming language created by [Niklaus Wirth](niklaus_wirth.md) in 1970. Pascal is a procedural programming language created by [Niklaus Wirth](niklaus_wirth.md) in 1970.
Pascal was a popular choice for microcomputers in the 70's and 80's, even more popular than C initially (C was still quite an UNIX-only language) Pascal was a popular choice for microcomputers in the 70's and 80's, even more popular than [C](c.md) initially (C was still quite an UNIX-only language)
due to its simple design, which allowed fast simple single-pass compilers. due to its simple design, which allowed fast simple single-pass compilers.
In its "vanilla" form, Pascal is not any more complex than C, aside from having features that C doesn't have, such as range types In its "vanilla" form, Pascal is not any more complex than C, aside from having features that C doesn't have,
and nested procedures. such as range types, nested procedures, sets, etc.
## Compilers ## Compilers
- [FPC](https://www.freepascal.org/) (Free Pascal Compiler): currently the most popular Pascal compiler with wide support - [FPC](https://www.freepascal.org/) (Free Pascal Compiler): currently the most popular Pascal compiler with wide support
for different OSes and architectures, libre software. for different OSes and architectures, libre software.
- Turbo Pascal: old compiler for DOS systems, proprietary. - Turbo Pascal: old compiler for [DOS](dos.md) systems, proprietary.
- Delphi: proprietary, adds [OOP](oop.md) bloat and exception handling. - Delphi: proprietary, adds [OOP](oop.md) [bloat](bloat.md) and [exception](exception.md) handling.
## Notes ## Notes
### Returning values from functions ### Returning values from functions
@ -54,21 +54,13 @@ fpc hellopascal.pas
### Factorial ### Factorial
```pascal ```pascal
{ {
Calculate a factorial on multiple languages: Pascal version Calculate a factorial on multiple languages: Pascal version
Compile with: fpc -O3 -S2 fact.pas Compile with: fpc -O3 -S2 fact.pas
} }
program Factorials; program Factorials;
{ qword = 64 bit unsigned type } { qword = 64 bit unsigned type }
function FactorialRec(n, acc: qword): qword; function Factorial(n: qword): qword;
begin
if n <= 0 then
Result := acc
else
Result := FactorialRec(n - 1, acc * n);
end;
function FactorialIter(n: qword): qword;
begin begin
Result := 1; Result := 1;
while n > 0 do while n > 0 do
@ -84,10 +76,9 @@ var
n: qword; n: qword;
values: array of qword = (14, 5, 2, 10, 1, 18, 4); values: array of qword = (14, 5, 2, 10, 1, 18, 4);
begin begin
Assert((FactorialIter(0) = 1) and (FactorialRec(0, 1) = 1));
for n in values do for n in values do
begin begin
WriteLn('Factorial of ', n, ' = ', FactorialRec(n, 1)); WriteLn('Factorial of ', n, ' = ', Factorial(n));
end; end;
end. end.
``` ```