**Parameters** in Pascal are the variables passed to a function or procedure. We use parameters to pass data we want to use in a function or procedure. There are four types of parameters in Pascal:


# Value parameters
**Value parameters** are the parameters that are passed by value. Passing parameters by value means that the function/procedure gets a copy of the parameters. 

The changes made to the parameter passed by value are not reflected in the original variable when the function/procedure returns.

# Syntax

Value parameters are passed to a *function* as follows:
```pascal
function (_parameterName_: _parameterType_): _returnType_;
begin
   //function body
end
```

Similarly, value parameters are passed to a *procedure* as follows:
```pascal
procedure (_parameterName_: _parameterType_);
begin
   //procedure body
end
```
* `_parameterName_`: The name of the value parameter.
* `_parameterType_`: The data type of the value parameter.
* `_returnType_`: The data type of the return value of the function.

>Note: The value parameters make heavy use of the stack as we make a copy of them. So, we must only use value parameters when required.

# Code
Consider the code snippet below, which demonstrates the use of the value parameters.

program function1;
var
   a, b, calSum : integer;
   
function sum(a, b: integer): integer;
begin
   a := a + b;
   sum := a;//store return value in variable having same name as the name of function
end;

begin
   a := 5;
   b := 10;
   writeln('');
   writeln('a before calling function = ',a);
   calSum := sum(a, b);
   writeln(a, ' + ', b, ' = ', calSum);
   writeln('a after calling function = ',a);
end.

pascal

# Explanation
A function `sum()` is declared in *line 5* that calculates the sum of two numbers passed to it as parameters. The parameters passed to the `sum()` function are *value parameters*. This is why changing the value of the parameter `a` is not propagated back when the function returns.

pascal.tar.gz

What are value parameters in Pascal?

Parameters in Pascal are the variables passed to a function or procedure. We use parameters to pass data we want to use in a function or procedure. There are four types of parameters in Pascal: 