Structured programming
In C it is good practice to break code into functions and group them into modules.
The paradigm of Structured Programming consists of identifying different functionalities and separating them into functions, thus avoiding having a very extensive code continuously because it makes its modification and maintenance very difficult.
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Variable scope
In C there is the concept of the scope of a variable
The scope refers to the visibility of a variable to define in which area of the program it can be used.
In C we can define code blocks by enclosing it between {. }
Variables defined within a block can only be used within that block and will not be visible outside of it.
These are the local variable calls that the compiler creates when starting a block and are automatically destroyed at the end of the block.
Global variables are those that are defined in a module and that are visible in all the functions created in that module.
Static variables are local variables defined in a function that maintain their value between different calls to the function.
Defining functions
A function can be defined in the form
Return name (parameters)
Return is the value that the function will return and can be a data type (int, float …) or void that is used to indicate that it does not return any value.
Name is the identifier of the function
Parameters is a comma separated list of variables that we will pass to the function.
E.g
float Calculate_Iva (float price, float vat)
Parameter passing by value
The most common way to pass parameters to a function is to pass them by value.
Constants or variables are passed that will not change value in the execution of the function.
float CalculateVAT (float price, float vat)
{
return price * vat / 100;
)
int main ()
(
float iva;
iva = CalculateVAT (1000, 21);
)
Parameter passing by reference
If we want a parameter of a function to be modified inside the function and return the modified value, the parameter can be used by reference.
In this case, instead of passing the value, a pointer is passed
E.g
float CalculateVAT (float price, float vat, float * pvp)
{
float pvat;
pvat= price * vat / 100;
* pvp = price + pvat;
return pvat;
)
int main ()
(
float vat, pvp
vat= CalculateVAT (1000, 21, & pvp);
)
This type of parameter passing is usually used when more than one value must be returned in the function.
