The document provides an overview of the basic structure of a C program, including sections like documentation, linking, definitions, and the main function. It covers key functions such as printf for output, scanf for input, clrscr() for clearing the screen, and getch() for waiting for keyboard input. Additionally, it includes sample programs and practice problems to reinforce learning objectives related to C programming.

1. C-Programming
Walchand Institute of Technology (RC1131), Solapur Page 1
Handout#2
Assignment/Program Statement:
Study basic structure of C program and write C programs using formatted input-
output functions, clrscr() function and getch() function in C.
Learning Objectives:
Students will be able to
- explain basic structure of C program
- explain printf, scanf, clrsrc() and getch() functions in C
- write C code using formatted input functions in C (i.e. scanf)
- write C code using formatted output functions in C (i.e. printf)
Theory:
[I] Basic Structure of C Program
Documentation Section
 This section consists of comment lines which include the name of
programmer, the author and other details like time and date of writing the
program.

2. C-Programming
Walchand Institute of Technology (RC1131), Solapur Page 2
 Documentation section helps anyone to get an overview of the program.
Link Section
 The link section consists of the header files of the functions that are used in
the program.
 It provides instructions to the compiler to link functions from the system
library.
Definition Section
 All the symbolic constants are written in definition section.
 Macros are known as symbolic constants.
Global Declaration Section
 The global variables that can be used anywhere in the program are declared
in global declaration section.
 This section also declares the user defined functions.
main() Function Section
 It is necessary have one main() function section in every C program.
 This section contains two parts, declaration and executable part.
 The declaration part declares all the variables that are used in executable
part.
 These two parts must be written in between the opening and closing braces.
 Each statement in the declaration and executable part must end with a
semicolon (;).
 The execution of program starts at opening braces and ends at closing
braces.
Subprogram Section
 The subprogram section contains all the user defined functions that are used
to perform a specific task.
 These user defined functions are called in the main() function.
[Reference: http://www.thecrazyprogrammer.com/2013/07/explain-basic-structure-of-c-
programs.html ]

3. C-Programming
Walchand Institute of Technology (RC1131), Solapur Page 3
Sample C Program:
#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf(“Hello World”);
getch();
}
[II] Basics of Formatted Input/Output in C
(A) Output with printf
 The basic format of a printf function call is:
printf (format_string, list_of_expressions);
where:
 format_string is the layout of what's being printed
 list_of_expressions is a comma-separated list of variables or expressions
yielding results to be inserted into the output
To output string literals, just use one parameter on printf, the string itself
printf("Hello, world!n");
printf("Greetings, Earthlingnn");
Sample C Program:
#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf(“Hello World”);
getch();
}
Header files required to use
built-in functions in C
main() function in C-program
C-function to clear screen
C-function to print
statement on screen
C-function to read a
key from keyboard

4. C-Programming
Walchand Institute of Technology (RC1131), Solapur Page 4
Conversion Specifiers:
A conversion specifier is a symbol that is used as a placeholder in a formatting
string. For integer output (for example), %d is the specifier that holds the place for
integers.
Here are some commonly used conversion specifiers (not a comprehensive list):
%d int (signed decimal integer)
%u unsigned decimal integer
%f floating point values (fixed notation) - float, double
%e floating point values (exponential notation)
%s string
%c character
 To output an integer, use %d in the format string, and an integer expression
in the list of expressions.
int totalStuds = 523;
printf("First Year of Engineering has %d students", totalStuds);
 Use the %f modifer to print floating point values in fixed notation:
double cost = 123.45;
printf("Your total is $%f todayn", cost);
(B) Input with scanf
 To read data in from standard input (keyboard), we call the scanf function.
 The basic format of a scanf function call is:
scanf(format_string, list_of_variable_addresses);
where:
 format_string is the layout of what's being read
 list_ of_variable_addresses is a comma-separated list of addresses variables
which specify space to store incoming data
 If x is a variable, then the expression &x means "address of x"
Example: int month, day;
printf("Please enter your birth month, followed by the day: ");
scanf("%d %d", &month, &day);

5. C-Programming
Walchand Institute of Technology (RC1131), Solapur Page 5
Conversion Specifiers
 Same as for output but with some small differences
 Use %f for type float, but use %lf for types double and long double
 The data type read, the conversion specifier, and the variable used need to
match in type.
 White space is skipped by default in consecutive numeric reads. But it is not
skipped for character/string inputs.
Example:
#include <stdio.h>
int main()
{
int i;
float f;
char c;
printf("Enter an integer and a float, then Y or Nn> ");
scanf("%d%f%c", &i, &f, &c);
printf("You entered:n");
printf("i = %d, f = %f, c = %cn", i, f, c);
}
(C) Interactive Input
 You can make input more interactive by prompting the user more carefully.
 This can be tedious in some places, but in many occasions, it makes
programs more user-friendly.
Example:
int rollNo, marks;
char answer;
printf("Please enter your Roll No: ");
scanf("%d", &rollNo);
printf("Please enter your marks: ");
scanf("%d",&marks);

6. C-Programming
Walchand Institute of Technology (RC1131), Solapur Page 6
printf("Do you want to continue (Y/N)? ");
scanf("%c",&answer);
[III] clrscr() function in C:
 It is built-in function in "conio.h" (console input output header file) used to
clear the console screen.
 It is used to clear the data from console (Monitor).
 Use of clrscr() function is always optional.
 This function should be place after variable or function declaration only.
[Reference: www.tutorial4us.com/cprogramming/c-clrscr-and-getch ]
[IV] getch() function in C:
 It is built-in function available under in "conio.h" (console input output
header file) will tell to the console wait for some time until a key is hit given
after running of program.
 This function can be used to read a character directly from the keyboard.
 Generally getch() are placing at end of the program after printing the output
on screen.
[Reference: www.tutorial4us.com/cprogramming/c-clrscr-and-getch ]
Example:
#include<stdio.h>
void main()
{
int rollNo, marks;
clrscr();
printf("Please enter your Roll No: ");
scanf("%d", &rollNo);
printf("Please enter your marks: ");
scanf("%d",&marks);
getch();
}

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Walchand Institute of Technology (RC1131), Solapur Page 7
Practice Problem Statements:
[Note: In following programs make use of clrscr() and getch() functions]
1) Write a program demonstrating scanf() function for addition of two numbers.
2) Write a program to read five subjects (Maths, BECP, Chemistry, Basic Civil &
Engineering Graphics) marks and display the average, percentage & total marks in
the following format
----------------------------------------------------------------------------------------
INPUT: Entered Marks
Maths : 85
BECP : 90
Chemistry : 80
Basic Civil : 75
Engineering Graphics : 92
---------------------------------------------------------------------------------------
OUTPUT:
Total Marks : 422
Average : 84.4
Percentage : 84.4%
----------------------------------------------------------------------------------------
Conclusion:
Thus we have studies the basic structure of C program, basic functions in C such as
printf to print and scanf to read. To clear screen, clrsrc() in C and to read key input
from keyboard getch(), we studied.
Learning Outcomes:
At the end of this assignment, students are able to
- explain basic structure of C program
- explain printf, scanf, clrsrc() and getch() functions in C
- write C code using formatted input functions in C (i.e. scanf)
- write C code using formatted output functions in C (i.e. printf)