FUNCTIONS IN C.pptx
- 2. FUNCTIONS • A function is a group of statements that together perform a task. • Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions. • A function declaration tells the compiler about a function's name, return type, and parameters. • A function definition provides the actual body of the function.
- 3. TYPES OF FUNCTIONS • Predefined standard library functions 1. Standard library functions are also known as built-in functions. Functions such as puts(), gets(), printf(), scanf() etc are standard library functions. 2. These functions are already defined in header files (files with .h extensions are called header files such as stdio.h), so we just call them whenever there is a need to use them. • User Defined functions 1. The functions that we create in a program are known as user defined functions or in other words you can say that a function created by user is known as user defined function.
- 4. DEFINING A FUNCTION • A function definition in C programming consists of a function header and a function body. Here are all the parts of a function − • Return Type − A function may return a value. The return_type is the data type of the value the function returns. • Function Name − This is the actual name of the function. The function name and the parameter list together constitute the function signature. • Parameters − A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. • Function Body − The function body contains a collection of statements that define what the function does.
- 5. EXAMPLE
- 6. FUNCTION DECLARATION • A function declaration tells the compiler about a function name and how to call the function. • The actual body of the function can be defined separately. • Function declaration is required when you define a function in one source file and you call that function in another file. • A function declaration has the following parts −
- 7. FUNCTION CALLING • While creating a C function, you give a definition of what the function has to do. • To use a function, you will have to call that function to perform the defined task. • When a program calls a function, the program control is transferred to the called function. • A called function performs a defined task and when its return statement is executed or when its function-ending closing brace is reached, it returns the program control back to the main program.
- 8. FUNCTION ARGUMENTS • While calling a function, there are two ways in which arguments can be passed to a function −
- 10. /* 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 : %dn", 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; }
- 11. Few Points to Note regarding functions in C: 1. main() in C program is also a function. 2. Each C program must have at least one function, which is main() 3. There is no limit on number of functions; A C program can have any number of functions. 4. A function can call itself and it is known as “Recursion“.