71. What happens to the statements written after return statement?

statement.

The return statement can be avoided if the return type is void. But if the return type in not void then in return statement, the expression to be returned must be of same type to that of the return type of the function.

74. What does function declaration suggest? How are function called?

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Functions are called with their name followed by the list of parameters or arguments. Function call must be used or assigned if the returned value should be taken into considerations. But if the function does not return any value or it returns a value which is not of much use then the function call need not be assigned to or used.

For example, simply calling power function which returns a value does not make any sense. pow(x,y);

But if it is assigned to a variable or used in some calculations then only it gives some meaning. z = pow(x,y);

z = a * pow(x,y)/b;

printf(“x to the power y is %f”, pow(x,y));

Let us take an example to calculate the largest number of three numbers, then Function declaration: int large(int, int, int);

Function call: l = large(a, b, c);

Function Definition: int large( int x, int y, int z) { }

Since, the type and number of arguments match in function declaration, call and definition, there would be no error. But if the number of arguments is changed, let us say in function call; l = large(a,b), then the compiler would give error. Similarly if the type of either variable a, b, c is not integer then again, it would result some kind of error. Hence, the number and type of arguments must be same in function declaration, function call and function definition.

Every entity in C programming must be declared before it is used. Declaration gives information not only to the user but also to the compiler about the type and name of the entity we are using. With such information, the compiler will interpret statements correctly. Also the compiler can decide how much storage space to allocate. Hence, every entity such as variables, functions must be declared first prior to its use. For example, without declaration, statement sum = num1 + num2 can represent

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sum of integers or sum of float numbers or even combining of characters or strings. This can cause problem to compiler.

77. Describe different types of functions based on return type and arguments.

void function_name(void);

clrscr(); is used to clear the screen with no arguments and no return type.

return_type function_name(void); where return type is not void

ch = getchar();

void function_name(argument list);

putchar(ch);

•Function with arguments and return type: This function, usually, contains only the processing part. The input and output of the problem will be in the calling function. The inputs will be passed as arguments while the result will be returned through return statement of function.

Return_type function_name(argument list); where return type is not void

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sq = sqrt(num);

The difference between library function and user defined function are listed below.

79. What do you mean by passing reference? When are they used?

statement, then in such situations passing reference are used.

80. Differentiate between pass by value and pass by reference.

void main();

{

int x = 2, y = 5; check(x, &y);

printf(“The final value of x is %d and y is %d”, x, y); getch();

}

void check(int a, int *b)

{

a = a+ 3; *b = *b + 2;

}

Here in this program, value of x is passed where address of y is passed. Variable a holds the value of x while pointer variable b holds the address of y. So, change in variable b represents change in variable y of main function but change in variable a does not change value of x in main function. Hence, the final value of x is 2 but the value of y is 7.