5. Introduction to ‘C’ language
Que 1 Fill in the blanks
1.
Errors
are mistakes in program, which are
traced by the compiler.
2.
Clrscr()
is the function which clears the previous output.
3.
C programming was designed and written
by Dennis Ritchie.
4.
C is a case sensitive
language.
5.
Variable are used to store
value or data of any type.
6.
getch()
is kept as the last statement of
the of the program so that after program
code gets executed and the output is printed on the screen.
7.
getch()
holds the screen so that output can be seen.
8.
Output can be seen on the screen with
the help of getch() function.
9.
C was developed at AT & T
Bell Laboratories of USA in 1972.
10.
The C compiler translates the C source program to machine
language.
11.
The output of the C compiler is called
object file.
12.
Object
file are saved with .obj extension.
13.
The linker combines
different object files to produce the
executable file.
14.
Keywords
are the reserved words used in programming.
15.
Keywords has the fixed meaning that can’t be changed by
the user.
16.
There are 32 keywords
available in C.
17.
Constants
are values that can’t be changed during the execution of a program.
18.
Variable are used to store value or data of any type.
19.
The value stored in a variable can change during the execution
of a program.
20.
Variables are names given to locations in the computer’s memory.
Que 2.Which rules must be follwed to
construct variable names?
Ans.
1) A
variable name should consist only alphabets,
digits and underscore, which can be short to reduce your typing effort.
2) First
character of variable name must be an alphabet or underscore.
3) No
commas, spaces, special symbols except
underscore should be present
in the variable name.
4) variable name should not exceed 31
characters.
5) Keywords can not be used as variable names.
Que 3. Identify the correct / incorrect variable names. Justify
your answer if the variable name is incorrect.
1.
Sum_1 :– Valid
2.
Add5 :– Valid
3.
6overs :– Invalid
6overs is an invalid variable because the
first character of a valid variable must be an alphabet or underscore. It can’t
be digit.
4.
Result value :– Invalid
Result value is an invalid variable because no
commas or spaces should be present in the variable name.
5.
Case :– Invalid
Case is a keyword of C language and keywords cannot
be used as variable names.
Que 4. Answer the following questions.
a)
What are key words?
Ø Keywords
are the reserved words used in programming.
Ø Keyword
has a fixed meaning and that cannot be changed by the user.
Ø There
are 32 keywords available in C.
Ø For
ex – auto, break, case, char, constant etc…
b)
Give any two features of C
programming?
Ø C
has a rich set of built-in functions.
Ø These
help us in re-using readily available programs.
Ø C
is a middle level language as it combines the capabilities of low level
programming with features of high level language.
Ø It
has a variety of ‘data types’ such as character, numeric and
alphanumeric.
Ø C
programs are highly portable since the program written in one computer
can be run on another computer.
c)
‘C is a case sensitive language’
justify the statement.
‘C is a case sensitive language’ because
commands written in uppercase and lowercase are not same.
For ex. Datatype int is not equal to INT
or Int.
d)
What are datatypes explain with
example.
Ø Datatypes
in c are used to define a variable before its use.
Ø It
specifies which type of data the variable can hold.
Ø C
has the following built – in data types.
1)
int – integer data type can be used to
store a whole number.
For ex - int a;
a = 5;
2)
char – character data type can be used
when we require storing a single character.
For ex - char ch;
ch = ‘y’;
3)
float – float data type is used when
we want to store decimal numbers.
For ex - float per;
Per = 55.67%
4)
double – double is also used t store
decimal numbers but it has more precision and higher range than float.
For ex – double per
Per = 2556784.2568;
Que 5. What is the use of getch() function?
getch()
is predefined function which accepts a character at the execution time. It
holds the screen till the user presses a key.
Que 5 Write down the steps to learn the C language.
Ans. The steps to learn C are:
Step 1 Alphabets,
Digits, Special symbols
Step 2 Constant,
Variable, Keywords
Step 3
Instructions
Step 4 Programs
Que 6 How to compile and execute a C program?
Ans. The process of converting a C
program into an executable program is done in 2 stages:
1)
Compiling 2)
Linking
The C compiler translates the C source program
to machine language or object file which
are saved with .obj extension and obj file also has information to aid the
linker.
The linker combines different object files
to produce the executable file with .exe
extension.
Que 7. Explain Data Type
Ans :
o
Data Types in C are used to define a
variable before its use.
o
It specifies which type of data
variable can store.
o
The type of data also declares how
much space it will require in the computer’s memory.
o
General syntax:
Data type var1, var2, var3 ….varn;
C has following built in data types:
1.
Int – used to store a whole number. It
can be positive or negative numbers like 1,-2 etc.
2.
Char – Character data type can be used
when we require storing a single character. The character can be an alphabet,
number, space or any special symbol.
3.
Float – Float is used when we want to
store decimal numbers. For ex. 55.67
4.
Double – Double is also used to store
decimal numbers, but it has more precision and higher range than float. For
ex 255584.35
Que 8. Explain Operators in
C.
Ans. An operator is a
symbol which instructs the compiler to perform a specific mathematical or
logical operation.
C
provides the following types of built-in operators:
v Arithmetic
Operators
The following table shows all the
arithmetic operators supported by the C language. Assume variable A holds
10 and variable B holds 20, then −
|
Operator
|
Description
|
Example
|
|
+
|
Adds two operands.
|
A + B = 30
|
|
−
|
Subtracts second
operand from the first.
|
A − B = 10
|
|
∗
|
Multiplies both
operands.
|
A ∗ B = 200
|
|
∕
|
Divides numerator by
de-numerator.
|
B ∕ A = 2
|
|
%
|
Modulus Operator and
remainder of after an integer division.
|
B % A = 0
|
v Relational
Operators
The following table
shows all the relational operators supported by C language. Assume
variable A holds 10 and variable B holds 20
then −
|
Operator
|
Description
|
Example
|
|
==
|
Checks if the values
of two operands are equal or not. If yes, then the condition becomes true.
|
(A == B) is not true.
|
|
!=
|
Checks if the values
of two operands are equal or not. If values are not equal then the condition
becomes true.
|
(A != B) is true.
|
|
>
|
Checks if the value of
left operand is greater than the value of right operand. If yes, then the
condition becomes true.
|
(A > B) is not
true.
|
|
<
|
Checks if the value of
left operand is less than the value of right operand. If yes, then the
condition becomes true.
|
(A < B) is true.
|
|
>=
|
Checks if the value of
left operand is greater than or equal to the value of right operand. If yes,
then the condition becomes true.
|
(A >= B) is not
true.
|
|
<=
|
Checks if the value of
left operand is less than or equal to the value of right operand. If yes,
then the condition becomes true.
|
(A <= B) is true.
|
v Logical
operators
Following table
shows all the logical operators supported by C language. Assume variable A holds
1 and variable B holds 0, then −
|
Operator
|
Description
|
Example
|
|
&&
|
Called Logical AND
operator. If both the operands are non-zero, then the condition becomes true.
|
(A && B) is
false.
|
|
||
|
Called Logical OR
Operator. If any of the two operands is non-zero, then the condition becomes
true.
|
(A || B) is true.
|
|
!
|
Called Logical NOT
Operator. It is used to reverse the logical state of its operand. If a
condition is true, then Logical NOT operator will make it false.
|
!(A && B) is
true.
|
v Assignment
operators
The following table
lists the assignment operators supported by the C language
|
Operator
|
Description
|
Example
|
|
=
|
Simple assignment
operator. Assigns values from right side operands to left side operand.
|
C = A + B will assign
the value of A + B to C
|
v Increment/Decrement
operator
Increment operators are used to increase the value of the variable
by one and decrement operators are used to decrease the value of the variable
by one in C programs.
|
++
|
Increment operator
increases the integer value by one.
|
A++ = 11
|
|
--
|
Decrement operator
decreases the integer value by one.
|
A-- = 9
|
Que 9. Write down the steps to write a c program.
§ C
program should be always written in the lower case.
§ All
the statements inside the function should end with a semicolon (;).
§ main
() is the first function.
§ All
the variable should be declared before using.
§ Every
opening brace or parenthesis should have a closing brace or parenthesis.
Que
10. Write a simple C program and explain it in detail.
1./*
First C program */
2.#include
<stdio.h>
3.#include
<conio.h>
4.void
main()
5.{
6.Clrscr
() ; // this statement clears the output screen
7.printf(“Hello
World! “);
8.getch();
9.}
1st
line – A comment in c begins with
/* and ends with */. Comments are non executable statements, used to add some
description or explanatory notes in a
program for documentation./* …… */ is used to
for multilane comments while // is used for single line comment.
2nd
line – Preprocessor directive: stdio.h is a standard input/output header
file. The #include is called a compiler directive and tells the compiler to
include a standard c library called stdio.h. Inbuilt c libraries are always
inside angle brackets < >.
3rd
line – This is again a preprocessor directive statement. We have included
console input/output header file since we are using its predefined functions
clrscr () and getch ().
4th
line – All the programming in C are made up of functions, and the one called
main always runs first.
The
name of this function is main, and since the function does not return
any value, the return data type of this function is void.
5th
line – Immediately after the function starts, code inside the function
should be written inside the curly
braces { }. This line contains the opening curly brace of the main
function.
6th
line – clrscr() is a predefined function
which clears the previous output from the output window. This function should be always kept at the
starting of the code. If kept after the code, it will result in blank output
since it will clear the output before letting us see it.
7th
line – printf () function is used to print the character, string, float,
integer, octal and hexadecimal values onto the output screen. The string or
character written inside the double quotes will print as it is in the output
screen. We can also use escape sequence characters in printf() function.
8th
line – getch () is predefined function which accepts a character at the
execution time. It holds the screen till the user pressed a key. It is kept as
the last statement of program so that after the program code gets executed and
the output is printed on the output screen, getch () function can hold the
screen so that the output can be seen.
9th
line – closing brace of main () function.
Que
11. Write down the steps to execute a C
program.
Step 1. Type the program and save the file
with .c extension.
Step
2. Press Alt + F9 to compile the
program. It will produce an object file.
Step
3. Press Ctrl + f9 to run the program. It will produce an executable file which
can be run anytime.
Que
12. What is escape sequence? Explain in detail.
Ans. An escape
sequence is two or more characters that often begin with an escape character
(backslash-\). They are used to represent new
line character, single quotation mark, or certain other special characters.
An escape sequence is regarded as a single character and is
therefore valid as a character constant.( text in Bold font can be asked in give
reason)
Following are some of the escape sequence characters used in
C.
|
\a
|
|
|
\b
|
|
|
\f
|
|
|
\n
|
Newline (Line Feed); see notes below
|
|
\r
|
|
|
\t
|
|
|
\v
|
|
Que
13.Explain errors of C programs in detail.
Ans.
Errors are mistakes in program, which are traced by the compiler while
compilation. A program can only execute when all the errors are corrected.
Types of errors:
1)
Logical errors – occur when the result we
get is not correct because of the incorrect code logic.
2)
Syntax : occur when the grammar of the C
language is not used properly.
For ex
1.
Typing Printf or print instead of printf.
2.
Forgetting a semicolon (;) at the end of an executable
C statement.
3.
Mismatch of parenthesis.
Que 14.Write a C program to add two
numbers.
#include<stdio.h>
#include<conio.h>
void main()
{
int
a, b, c;
clrscr();
a
= 5;
b = 2;
c
= a + b;
printf ("Sum is = %d\n",c);
getch();
}
Que 15. Explain
Format Specifiers.
Ans. Format
Specifiers are % sing followed by a letter which actually prints the value of
the variable. Following are the list of format specifiers used in C to print
the value of variables of different types.
|
%c
|
Character
format Specifiers
|
|
%d
|
Signed
Integer format Specifiers
|
|
%f
|
Floating
point format Specifiers
|
|
%lf
|
Floating
point format Specifiers
|
|
%s
|
String
format Specifiers
|
|
%u
|
Unsigned
Integer format Specifiers
|
|
%n
|
Prints
nothing
|
|
%%
|
Prints
% character
|
Note :-
1. Cycle Test - 3 - Computer Syllabus - Chapter 4 & 5
2.Chapter 4 material is already uploaded on 24th Nov. 2015.
3.For better exam preparation students are suggested to refer textbook and work book along with this material.
