1. Sigma institute of engineering SUBJECT: COMPUTER PROGRAMMING
AND UTILIZATION PREPARED BY : group c ENROLLMENT NO:- NAME OF
STUDENT 1. 140500119041 KANADE MAHENDRA 2. 140500119052 MAKWANA
BHAVESH 3. 140500119054 MEHUL JHALA ASSIGNED BY ; PROF.SURESH
CHAUDHARY 2. Topic : functions 3. CONTENTS: Function Function
example Vedio on functions Benefits of function Math library
functions function prototype Function arguments C++ variables
Global variable External variables Other variables Recursion
Recursion example 4. Functions A function is a self contained block
of code that performs a particular task. Any C program can be seen
as a collection/group of these functions. A functions takes some
data as input, perform some operation on that data and then return
a value. Any C program must contain at least one function, which is
main(). There is no limit on the number of functions that might be
present in a C program. 5. For ex. main() { message(); printf(I am
in main); } message() { printf(I am in message); } 6. Video on
function 7. Benefits of functions Divide and conquer Manageable
program development Software reusability Use existing functions as
building blocks for new programs Abstraction - hide internal
details (library functions) Avoid code repetition 8. 5.3Math
Library Functions Math library functions perform common
mathematical calculations #include Format for calling functions
FunctionName( argument ); If multiple arguments, use
comma-separated list printf( "%.2f", sqrt( 900.0 ) ); Calls
function sqrt, which returns the square root of its argument All
math functions return data type double Arguments may be constants,
variables, or expressions 9. Method Description Example ceil( x )
rounds x to the smallest integer not less than x ceil( 9.2 ) is
10.0 ceil( -9.8 ) is -9.0 cos( x ) trigonometric cosine of x (x in
radians) cos( 0.0 ) is 1.0 exp( x ) exponential function ex exp(
1.0 ) is 2.71828 exp( 2.0 ) is 7.38906 fabs( x ) absolute value of
x fabs( 5.1 ) is 5.1 fabs( 0.0 ) is 0.0 fabs( -8.76 ) is 8.76
floor( x ) rounds x to the largest integer not greater than x
floor( 9.2 ) is 9.0 floor( -9.8 ) is -10.0 fmod( x, y ) remainder
of x/y as a floating- point number fmod( 13.657, 2.333 ) is 1.992
log( x ) natural logarithm of x (base e) log( 2.718282 ) is 1.0
log( 7.389056 ) is 2.0 log10( x ) logarithm of x (base 10) log10(
10.0 ) is 1.0 log10( 100.0 ) is 2.0 pow( x, y ) x raised to power y
(xy) pow( 2, 7 ) is 128 pow( 9, .5 ) is 3 sin( x ) trigonometric
sine of x (x in radians) sin( 0.0 ) is 0 sqrt( x ) square root of x
sqrt( 900.0 ) is 30.0 sqrt( 9.0 ) is 3.0 tan( x ) trigonometric
tangent of x (x in radians) tan( 0.0 ) is 0 Fig. 3.2 Math library
functions. Math Library Functions Revisited 10. 5.2Program Modules
in C Functions Modules in C Programs combine user-defined functions
with library functions C standard library has a wide variety of
functions Function calls Invoking functions Provide function name
and arguments (data) Function performs operations or manipulations
Function returns results Function call analogy: Boss asks worker to
complete task Worker gets information, does task, returns result
Information hiding: boss does not know details 11. Function
Prototype All Identifiers in C must be declared before they are
used. This is true for functions as well as variables. For
functions, the declarations needs to be done before the first call
of the function. A function declaration specifies the name, return
type, and arguments of a function. This is also called the function
prototype. To be a prototype, a function declaration must establish
types for the functions arguments. Having the prototype available
before the first use of the function allows the compiler to check
that the correct number and types of arguments are used in the
function call. 12. The prototype has the same syntax as the
function definition, except that it is terminated by a semicolon
following the closing parenthesis and therefore has no body.
Although, functions that return int values do not require
prototypes, prototypes are recommended. 13. Function Definition
General form of any function definition is: return-type
function-name(argument declarations) { declarations and statements
} Return-type refers to the data type of the value being returned
from the function. If the return type is omitted, int is assumed.
The values provided to a function for processing are the arguments.
The set of statements between the braces is called as the function
body. 14. Arguments Call by Value In C, all functions are passed by
value by default. This means that the called function is given the
values of its arguments in temporary variables rather than the
originals. For ex. main() { int a=4,b=5; sum(a,b); printf(Sum =
%d,a+b); } sum(int a,int b) { a++; b++; printf(Sum = %d,a+b); } 15.
Arguments Call by Reference When necessary, it is possible to
arrange a function which can modify a variable in a calling
routine. The caller must provide the address of the variable to be
set (generally, a pointer to a variable), and the called function
must declare the parameter to be a pointer and access the variable
indirectly through it. For ex: main() { int a=4,b=5;
sum(&a,&b); printf(Sum = %d,a+b); } sum(int *a,int *b) {
(*a)++; (*b)++; printf(Sum = %d,(*a)+(*b)); } 16. C++ Variables A
variable is a place in memory that has A name or identifier (e.g.
income, taxes, etc.) A data type (e.g. int, double, char, etc.) A
size (number of bytes) A scope (the part of the program code that
can use it) Global variables all functions can see it and using it
Local variables only the function that declare local variables see
and use these variables A life time (the duration of its existence)
Global variables can live as long as the program is executed Local
variables are lived only when the functions that define these
variables are executed 16 17. Local Variables Local variables are
declared inside the function body and exist as long as the function
is running and destroyed when the function exit You have to
initialize the local variable before using it If a function defines
a local variable and there was a global variable with the same
name, the function uses its local variable instead of using the
global variable 17 18. Example of Defining and Using Global and
Local Variables #include int x; // Global variable Void fun(); //
function signature void main() { x = 4; fun(); cout
