Methods in C##

Methods in C##

A function is a collection of statements that work together to complete a job. Every C programme contains at least one function, main(), and even the simplest programmes can specify more functions.

You may break your code into different functions. It's up to you how you split your code into various functions, but logically, each function should fulfil a specific purpose.

The name, return type, and parameters of a function are all specified in a function declaration. The actual body of the function is provided by a function definition.

The C standard library includes a number of built-in functions that you may use in your application. Strcat(), for example, concatenates two strings, memcpy() copies one memory address to another, and many other methods.

A function is sometimes known as a method, a subroutine, a process, and so on.

Defining a Function

In the C programming language, a function definition takes the following general form:

return_type function_name( parameter list ) { body of the function }
  • In C programming, a function definition consists of a function header and a function body. All of the components of a function are listed here.
  • A function may return a value as its return type. The return type specifies the data type of the value returned by the function. Some functions do what they're supposed to do yet don't return a value. The term void is used as the return type in this situation.
  • Function Name This is the function's real name. The function signature is made up of the function name and the argument list.
  • A parameter is similar to a placeholder. You send a value to the argument when you call a function. An actual parameter or argument is the name given to this item. The type, order, and number of parameters of a function are referred to as the parameter list. Parameters are optional; a function may or may not have them.
  • The function body is made up of a set of statements that describe what the function performs.

Example

The source code for a function named max is shown below (). The greatest value between two arguments, num1 and num2, is returned by this function.

/* function returning the max between two numbers */ int max(int num1, int num2) { /* local variable declaration */ int result; if (num1 > num2) result = num1; else result = num2; return result; }

Function Declarations

A function declaration gives the compiler the name of the function and how to invoke it. The function's actual body can be specified independently.

Return type function name( parameter list ); return type function name( parameter list ); return type function name( parameter list ); return type function name( parameter list ); return type

The function definition for the above-mentioned function max() is int max(int num1, int num2);

The names of the parameters are unimportant in function declarations; just their types are necessary, thus the following declaration is equally legal.

int max(int, int);

When a function is defined in one source file and called in another, a function declaration is necessary. In this instance, the function should be declared at the start of the file invoking the function.

Calling a Function

When you create a C function, you must define what the function must perform. To utilise a function, you must first call it to accomplish the specified job.

When a programme calls a function, control is passed from the calling programme to the called function. A called function performs a specific job and then returns programme control to the main programme when its return statement or function-ending closing brace is reached.

You just need to supply the appropriate arguments along with the function name to call a function, and if the function returns a result, you may save it. For instance,

#include <stdio.h> /* function declaration */ int max(int num1, int num2); int main () { /* local variable definition */ int a = 100; int b = 200; int ret; /* calling a function to get max value */ ret = max(a, b); printf( "Max value is : %d\n", ret ); return 0; } /* function returning the max between two numbers */ int max(int num1, int num2) { /* local variable declaration */ int result; if (num1 > num2) result = num1; else result = num2; return result; }

We compiled the source code while keeping max() and main(). When you execute the finished executable, you'll get the following result:

Max value is : 200

Function Arguments

If a function is going to utilise arguments, it has to define variables that will take the arguments' values. These variables are known as the function's formal parameters.

Formal arguments are generated when the function is entered and deleted when it is exited, just like other local variables inside the function.

There are two methods to give parameters to a function when calling it: