The document provides an overview of key concepts in C programming including variables, data types, operators, control flow structures like decisions and loops, and functions. It discusses how computers perform simple tasks like addition via inputs, storage in memory, processing, and outputs. Examples are provided to illustrate concepts like printf formatting, if/else statements, for/while loops, and break/continue keywords. Self-check questions review variable definitions, loop execution, and output of sample programs.

1. Recall
• What is a variable?
• How doe the CPU Execution flow occurs?
Random or sequential?
• What are the options to control the normal
flow of executions?
• What is a function? When do we use
functions?

2. Introduction to C
Week 2

3. How does human perform simple task; for
Eg: add 456 and 44
Add 456
and 44 500

4. How does human perform simple task;
Eg: add 456 and 44
1 We Hear it through our input senses
2 We store the numbers 456 and 44 in our memory
456
44
456+44 3 We calculate the result in our brain and store it in
memory
500
3 We say the answer through our output senses

5. 1 Computer use keyboard to receive inputs
2 Computer store the numbers 456 and 44 in Ram
456
44
456+44
3
Computer calculate the result in CPU (ALU within
CPU) and stores result back in ram
500
4 Computer use monitor to display outputs
How does computer perform simple
task; Eg: add 456 and 44

6. – Start
– Get two numbers and
store them
– Add them and store
the result
– Print the answer
– End
Algorithm

7. – Start
– Get two numbers and
store them
– Add them and store
the result
– Print the answer
– End
Main
{
int a,b,c;
a=456,b=44;
c= a+b;
// something to print the value
from c, will discuss soon
}
Algorithm Vs
Program
500
44
456
b
a
c

8. main()
{
int a=456, b=44,c;
c= a+b;
printf (“%d”,c); // So who defined this function??
Where is it located?
}

9. #include < stdio.h >
main()
{
int a=456, b=44,c;
c= a+b;
printf (“%d”,c);
}
........
Printf(..)
{
........
}
Scanf (..)
{.....
}
Stdio . h

10. Printf()
• Printf(“%d”,c)
– %d refers to Format specifier which is used
to specify the type and format of the data to
be taken to the stream and to be printed on
screen
• %f -> for float data type
• %c for Char data type
• %s for string data type
–c refers to the value of location named
c
500
44
456
b
a
c

11. –%d refers to Format specifies
which is used to specify the type
and format of the data to be
retrieved from the stream and
stored into the locations pointed by
&a.
–&a refers to the memory address of
location named a
scanf()

12. Complete Program
#include < stdio.h >
main()
{
int a,b,c;
Scanf(“%d %d”,&a,&b);
c= a+b;
printf (“%d”,c);
}

13. Elements of C
• Variables
• Operators
• Control structures
 Decision
 Loops
• functions

14. Variables in C

15. Variables
int a;
Data type variable name

16. Variables
Data type
• Data type is the type of data we are going to store
in the reserved Ram location.
• We need to specify the data type so that size to be
allocated will be done automatically.
 Int -> reserves 2 bytes of memory
 Char -> reserves 1 byte of memory
 float -> reserves 4 bytes of memory
Variable Name
• Variable is the name we give to access the value
from the memory space we allocate.
• Variable name should begin with characters or _ ;But

17. Variables
• Naming a Variable
– Must be a valid identifier.
– Must not be a keyword
– Names are case sensitive.
– Variables are identified by only first 32
characters.
– Library commonly uses names beginning with
_.
– Naming Styles: Uppercase style and
Underscore style

18. Decisions in C

19. N Y
Start
i=1
If
i<100
Print iStop
Print all the numbers up to 100
i=i+1

20. Decisions
• Eg: if(i=100)
{
printf(“You are a low performer”);
}
else
{
printf(“You are a top performer”);
}

21. Nested if
• Eg: if(i==0)
{
printf(“You are a low performer”);
}
else if(i==200)
{
printf(“You are a top performer”);
}
Else if (i==300)
{
…
}

22. What is “=“ and “==“
=
– As discussed earlier = is used to assign a
value into a location we reserved already/or to
assign value in to a variable
– Eg: a=10
==
– Is used to check whether the value of a
variable is equal to the value provided in the
other side of operand

23. switch
Switch(i)
{
Case 0:
printf(“poor performer”);
break;
Case 100:
printf(“Good performer”);
break;
Case default:
printf(“performer”);
break;
}

24. switch
Switch(i)
{
Case 0:
printf(“poor performer”);
break;
Case 100:
printf(“Good performer”);
break;
Case default:
printf(“performer”);
break;
}
if(i==0)
{
printf(“Poor Performer”)
}
else if(i==100)
{
printf(“Good performer”
}
Else {
Printf(“performer”);
}

25. Loops in c

26. N Y
Start
i=1
If
i<100
Print iStop
Print all the numbers up to 100
i=i+1

27. Loops in C
• For loop
• While Loop
• Do While Loop

28. For Loop
for
(i=0;i<50;i++)
{
printf(“%d ”, i);
} // {braces} are not
necessary if there is only
one statement inside for
loop
Step 1 : i=0 :
initialization
Step 2 : i<50 : if
true step 3
or else step 6
Step 3 : {
executes }
Step 4 : i++

29. While Loop
i=0;
While(i<50)
{
printf(“%d ”, i);
i++;
} // {braces} are not
necessary if there is only
Step 1 : i=0 :
initialization
Step 2 : i<50 : if
true step 3
or else step 6
Step 3 : {
executes }
Step 4 : i++

30. Do while Loop
i=0;
Do
{
printf(“%d ”, i);
i++;
} While(i<50)
Step 1 : i=0 :
initialization
Step 3 : {
executes }
Step 4 : i++
Step 2 : i<50 : if
true step 3 or

31. Other Control statements
• Break Statements
– The break statement terminates the
execution of the nearest
enclosing do, for, switch, or while statement
in which it appears.
• Continue statements
– The continue statement works like
the break statement. Instead of forcing
termination, however, continue forces the next
iteration of the loop to take place, skipping

32. Example
int a = 10;
while( a < 20 )
{
printf("value of a: %d n", a);
a++;
if( a > 15) {
break;
}
}

33. Example
int a = 10;
while( a < 20 )
{
printf("value of a: %d n", a);
a++;
if( a > 15) {
break;
}
}
Output
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 15

34. Example
int a = 10;
do
{
If( a == 15)
{
a = a + 1;
continue;
}
printf("value of a: %dn", a);
a++;
} while( a < 20 );

35. Example
int a = 10;
do
{
If( a == 15)
{
a = a + 1;
continue;
}
printf("value of a: %dn", a);
a++;
} while( a < 20 );
Output
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 16
value of a: 17
value of a: 18
value of a: 19

36. Operators
• Arithmetic Operators
+, - , *, / and the modulus operator %.
• Relational operators
<, <=, > >=, ==, !=
• Logical operators
&&, ||, ! eg : If (a<10 && b>9)
• Assignment Operators
=, += ,-= eg: a+=10//same as
a=a+10
• Increment and decrement operators

37. Difference between i++ and ++i
• ++i Increments i by one, then returns i.
• i++ Returns i, then increments i by one.
i=10,j=20
Z=++i;
W=j++;
Printf(“%d %d”, z,w); // w=20; z=11

38. Questions?
“A good question deserve a good
grade…”

39. Self Check !!

40. Self-Check
• What is a difference between a declaration and a
definition of a variable?
– Both can occur multiple times, but a
declaration must occur first.
– There is no difference between them.
– A definition occurs once, but a declaration
may occur many times.
– A declaration occurs once, but a definition
may occur many times.
– Both can occur multiple times, but a definition

41. Self-Check
• What is a difference between a declaration and a
definition of a variable?
– Both can occur multiple times, but a
declaration must occur first.
– There is no difference between them.
– A definition occurs once, but a declaration
may occur many times.
– A declaration occurs once, but a definition
may occur many times.
– Both can occur multiple times, but a definition

42. Self-Check
• How many times “baabtra“ get printed?
main()
{
int x;
for(x=-1; x<=10; x++)
{
if(x < 5)
continue;
else
break;
printf(“baabtra");
}
}
1.Infinite
times
2.11 Times
3.0 times
4.10 times

43. Self-Check
• How many times “baabtra“ get printed?
main()
{
int x;
for(x=-1; x<=10; x++)
{
if(x < 5)
continue;
else
break;
printf(“baabtra");
}
}
1.Infinite
times
2.11 Times
3.0 times
4.10 times

44. Self-Check
What is the output of the following program?
void main()
{
int i=10;
switch(i)
{
case 1: printf(" i=1");
break;
case 10: printf(" i=10");
case 11: printf(" i=11");
break;
case 12: printf(" i=12");
}
}
1. i=10 i=11
i=12
2. i=1 i=10
i=11 i=12
3. i=10 i=11
4. None of
above

45. Self-Check
What is the output of the following program?
void main()
{
int i=10;
switch(i)
{
case 1: printf(" i=1");
break;
case 10: printf(" i=10");
case 11: printf(" i=11");
break;
case 12: printf(" i=12");
}
}
1. i=10 i=11
i=12
2. i=1 i=10
i=11 i=12
3. i=10 i=11
4. None of
above

46. Self-Check
What is the output of the following program?
void main()
{
int i=1,j=1;
while (++i < 10)
printf("%d ",i);
printf("n");
while (j++ < 10)
printf("%d ",j);
}
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10
2 3 4 5 6 7 8 9
2 3 4 5 6 7 8 9 10
2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10

47. Self-Check
What is the output of the following program?
void main()
{
int i=1,j=1;
while (++i < 10)
printf("%d ",i);
printf("n");
while (j++ < 10)
printf("%d ",j);
}
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10
2 3 4 5 6 7 8 9
2 3 4 5 6 7 8 9 10
2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10

48. End of Day 1