Write about Different Categories of Functions in C?

A function depending on whether rays are present or not and whether a value is returned or not, may belong to one of the follow categories. Categories: 1: Function with no arguments and no return values 2. Functions with arguments and no return values 3. Functions with arguments and one return value 4. Functions with no arguments but return a value 5. Functions that return multiple values.

1. No arguments and no return values: When a function has no arguments, it does not receive any data from the calling function similarly, when it does not return a value, the calling fiction does not receive any data from the called function. There is no data transfer but the calling function and the called function. Ex://Funciton declaration void display ( void); main ( ) { display ( ); } void display ( void)  // contains no arguments { printf (“Degree College”); }

Arguments but no return values:

The nature of data com: but the calling function of the called function with arguments but no return value is shown below. Ex: void print ( char ch) void value ( float p, int n) The arguments ch, p, n are called formal arguments. The calling function can now send values to these arguments using function call containing appropriate arguments as value ( 5.26,8) Assign 5.26 to p and 8 to n. The values 5.26 and 8 are called actual arguments with become the values of the formal arguments inside the called function. The actual and formal arguments should match in number, type and order. The values of actual arguments are assigned to the formal arguments on a one to one basis, starting with the 1st argument. The variables used in actual arguments must be assigned values before the function call is made. When a function call is made, only a copy of the values of actual arguments is passed into the called function. What occurs inside the function will have no effect on the variables used in the actual arguments list. One way data communication Ex: void printline ( char ch); main ( ) { printline (z); printf ( “\n”); printline (A); } void printline ( char ch) { int i; for ( i =1; i < 10; i++) printf ( “\t %c”, ch); printf  ( “\n”); } OP: zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz        AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

Arguments with return values:

However, we may not always wish to have the result of a function displayed. We may use it in the calling in for further processing. Two –way data communication between functions Ex: int product ( int x, int y) { int z; z = x * y; return ( z); } main ( ) { int a, b, c; printf ( “enter 2 values”); scanf ( “%d% d”, &a,& b); c=product ( a, b); printf (“product is %d”c); geteh ( ); } C function returns a value of the type int as the default case when no other type is specified explicitly. If the function calculates the mean and standard deviation of a set of values should return either float or double. In such cases, we must specify the return type in both the function definition and the prototype declaration.

No arguments but return a value:

There could be occasions where we may need to design functions that may not take any arguments but returns a value to the calling function. For example the get char function has no parameters but it returns as integer type data that represents a character. Ex: int get_no (void); main ( ) { int m = get_no ( ); printf (“%d”,m); } int get_no ( void) { int no; scanf (“%d”,&no); return ( no); }

Functions that return multiple values:

Functions that return just one value using a return statement because a return statement can return only one value.

It we want to get more info. Form a function we can achieve this in C using the rays not only to receive info; but also to send back information to the calling function. The arguments that are used to send out info one called output parameters. The mechanism of sending back information through arguments is achieved using what are known as the address operator  (&) and indirection operator ( * ).

Example: void mathop (int x, int y, int *s, int *diff) { int x = 20, y = 10, s, d; mathop(x, y, &s, &d); printf(“sum=%d \n difference=%d\n”,s,d); } void method ( int a, int b, int * sum, int * diff) { * sum = a+b; * diff = a-b; } The actual arguments x & y are input arguments s & d are output arguments. When the function is called the following assignments occur: Value of x to a Value of y to b  //  pass the values Address of S to sum d to diff // Pass the address where the values of s and d stored                                                    in memory.          The value of a+b is stored in the location printed by sum. The value of a-b is stored in the memory location pointed by diff, while is the same as the location d.