CS 1106 - UNIT -3 notes for students to learn

CS 1106
PROGRAMMING
LANGUAGES
Prepared By
Dr. Prabakaran Narayanan

Functions,
Structure
&
Union
Unit -3

3.1. Built-in Functions
3.1.1. Math functions
3.1.2. Console I/O functions
3.1.3. Standard I/O functions
3.1.4. Character Oriented Functions

3.1. What is Built-in Functions in C
or
What is in-built Functions in C
or
What is library functions in C
 Each built-in function in C performs specific operation
 We can use of these built-in functions to get the pre-defined
output instead of writing our own code for those outputs.
 Ex: scanf(), printf(), sin(), cos(), getch(),strcat(),strcmp()

3.1.1. Math Functions : #include <math.h>
Math operations Meanings
sin(x) Sine of (x)
cos(x) Cosine of (x)
tan (x) Tangent of (x)
pow(x,y) X to the power of y
sqrt(x) Square root of x

3.1.1. Math Functions : #include <math.h>
Ex.no.12 . Math.h operations

3.1.2. Console Input Output functions

1.17.Formatted Input
Formatted input to an input data that has been arranged in a
particular format
Syntax:
scanf(“Format Specifier”, &var1, &var2, …., &varn);
Ex:
scanf(”%d %d” , &a,&b)

1.getch(): to read a character from the keyboard
Ex: x=getch();
2.putch(): to display a character on the monitor
ex: printf(“%c”, putch(x));
3.gets() : to read a string of characters including white spaces from
the keyboard
Ex: gets(name);
4.puts(): to display string of characters including white spaces on
the monitor Ex: puts(name);
3.1.3. Character oriented Input Output functions

CS 1106 - UNIT -3 notes for students to learn

3.2. User –defined functions
A function is a self-contained block of code that
perform a particular task.
syntax
void function_name(argument list)
{
local variable declarations;
executable statements-1;
……………………
……………………
}

3.2. User –defined functions (cont..)
void function_name(argument list)
{
……………………
……………………
}
Where
function_name  user defined name
Argument list  surrounded by parenthesis
contains valid variable names separated by commas
Ex:
void square(int x)
{
int res;
res = x*x;
printf(“Square is “%d”, res);
}

3.1.2. Find square of given number using user
defined function
#include<stdio.h>
#include<conio.h>
void square(int x)
{
int res;
res = x*x;
printf(“Square is “%d”, res);
}
void main()
{
int s;
scanf(“%d”, &s);
square(s);
}

3.2.1. User –defined functions with return values
return type function_name(argument list)
{
……………………
……………………
return(value);
}
Where
return type  data type of return value
function_name user defined name
Return(value)  Taking value from user
defined function to main function
Ex
int addition(int x, int y)
{
int sum;
sum = x + y;
return(sum);
}

Ex.no.13. Find square of given number using user
defined function with return type
#include<stdio.h>
#include<conio.h>
int square(int x)
{
int res;
res = x*x;
return res;
}
void main()
{
int s,res;
res= square(s);
printf(“square of a given number is %d” , res);
}
Calling fn
Called fn

3.3. Function Prototype
 Definition: A function prototype is a declaration of a function that
specifies the function’s name & type (data type & return type) but
omits the function body
 Ex: returntype function_name (arg1, arg2, ……);
#include <stdio.h}
#include<conio.h>
int add(int x);  function prototype for add
void main()
{
……………………..
}
int add( int x)
{…………………… }

#include<stdio.h>
#include<conio.h>
int square(int x) ;
void main()
{
int s,res;
res= square(s);
printf(“square of a given number is %d” , res);
}
int square(int x)
{
int res;
res = x*x;
return res;
}
Called fn
Prototype
Calling fn
3.3. Function Prototype (cont..)

3.4. Recursion
 If a program allows you to call a function inside the same function
 Recursion is the process of repeating items in a self-similar way
void main()
{
printf(“This is an example of recursion “);
main();
}
Execution is terminated abruptly ;otherwise the execution will
continue indefinitely
Output: This is an example of recursion
This is an example of
recursion
recursion
recursion
This is an examp

3.4. Recursion (cont..)
void fact()
{
printf(“Welcome”);
fact();
}
void main()
{
fact();
}
Output: welcome
welcome
welcome
welcome

3.5. Structure
Definition:
It is used to create a collection of data
items of different data types using a
single name

3.5.1. Structure Declaration
struct tag name
{
datatype member variable1;
datatype member variable 2;
……………..
………………
} ;
void main()
{ struct tagname structure_name;
}
Ex:
struct student
{
char name[20];
int regno;
char branch[10];
} ;
void main()
{
struct student stud;
}

3.5.2. Accessing Member variable
 To access the member variable in structure
syntax:
struct_name . member variable;
Reading inputs through keyboard:
scanf(“%s”, &stud.name);
scanf(“%d”, & stud.regno);
scanf(“%s”,&stud.branch);
Ex:
struct student
{
char name[20];
int regno;
char branch[10];
} ;
void main()
{
}

3.5.3. Structure Initialization
Syntax:
struct tag name st_name={value1, value2,…. }
Ex:
Struct student stud={“Mansoor ”, 213836, “Civil”};
name
regno
branch
b.
Ex:
struct student
{
char name[20];
int regno;
char branch[10];
} ;
void main()
{
}

Ex. No. 14. Write a C program to print
student details using structure
#include<stdio.h>
#include<conio.h>
struct student
{
char name[20];
int regno;
char branch[10];
} ;
void main()
{
scanf(“%s”, &stud.name);
scanf(“%d”, & stud.regno);
scanf(“%s”,&stud.branch);
printf(“%s”, stud.name);
printf(“%d”, stud.regno);
printf(“%s”, ”,stud.branch);
}

3.5.3. Array of
Structure
title
page
price
stud[1].
title
page
price
stud[2].
price
page
title
stud[3].
Ex:
struct student
{
char name[20];
int regno;
char branch[10];
} ;
void main()
{
struct student
stud[3];
}

Ex. No. 15. Write a C program to print Book details using
array of structure
#include<stdio.h>
#include<conio.h>
struct student
{
char name[20];
int regno;
char branch[10];
} ;
void main()
{
struct student stud[3];
for (i=1; i<=5; i++)
{
scanf(“%s”, &stud[i].name);
scanf(“%d”, & stud[i].regno);
scanf(“%s”,&stud[i].branch);
}
for(i=1; i<=5; i++)
{
printf(“%s”, stud[i].name);
printf(“%d”, stud[i].regno);

CS1106- Programming Languages- Assignment No. 1
 1. Write a C program to find sum of n numbers:
 2. Write a C program to find factorial of a given number
 3. Write a C program to find sum of digits of a number:
 4. Write a C Program to Reverse the given number:
 5. Write a C Program to find number is Armstrong number or not
 6. Write a C Program to check the number is palindrome or not
 7. Write a C to print numbers divisible by 5 not by 10:
 8. Write a C Program to print fibonacci series.
 9. Write a C program to Check the given number is prime or not
 10. Write a C program to Print first n prime numbers
Deadline for submission
on 18.12.2023
All variables should use your names

3.6. Union
union tag name
{
datatype member variable1;
datatype member variable 2;
……………..
………………
} ;
void main()
{ union tagname union_name;
}
Ex:
union student
{
char name[20];
int regno;
char branch[10];
} ;
void main()
{
union student stud;
}

3.6. Union
 Unions are a concept borrowed from
structure and therefore follow same
syntax as structure
 Major distinction between them in
terms of storage
 In structure each member has its own
storage location, where as all the
members of a union use the same
memory location

CS 1106 - UNIT -3 notes for students to learn

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