This about C program

1. C Syntax
#include <stdio.h>
int main() {
printf("Hello World!");
return 0;
}

2. Output (Print Text)
To output values or print text in C, you can use
the printf() function:
#include <stdio.h>
int main() {
printf("Hello World!");
return 0;
}

3. New Lines
To insert a new line, you can use the n character:
#include <stdio.h>
int main() {
printf("Hello World!n");
printf("I am learning C.");
return 0;
}

4. Comments in C
 Comments can be used to explain code, and to make it more
readable. It can also be used to prevent execution when testing
alternative code.
 Comments can be singled-lined or multi-lined.
 Single-line comments start with two forward slashes (//).
 Any text between // and the end of the line is ignored by the
compiler (will not be executed).
 // This is a comment
printf("Hello World!");

5. Comments in C
 C Multi-line Comments
 Multi-line comments start with /* and ends with */.
 Any text between /* and */ will be ignored by the compiler
 /* The code below will print the words Hello World!
to the screen, and it is amazing */
printf("Hello World!");

6. C Variables
 Variables are containers for storing data values, like numbers
and characters.
 In C, there are different types of variables (defined with
different keywords), for example:
 int - stores integers (whole numbers), without decimals, such as
123 or -123
 float - stores floating point numbers, with decimals, such as
19.99 or -19.99
 char - stores single characters, such as 'a' or 'B'. Characters are
surrounded by single quotes

7. C Variables
 // Declare a variable
int myNum;
// Assign a value to the variable
myNum = 15;

8. C Format Specifiers
 Format specifiers are used together with the printf() function to
tell the compiler what type of data the variable is storing. It is
basically a placeholder for the variable value.
 A format specifier starts with a percentage sign %, followed by
a character.
 For example, to output the value of an int variable, use the
format specifier %d surrounded by double quotes (""), inside
the printf() function:
 Example
 int myNum = 15;
printf("%d", myNum); // Outputs 15

9. C Format Specifiers
To print other types, use %c for char and %f for float:
// Create variables
int myNum = 15; // Integer (whole number)
float myFloatNum = 5.99; // Floating point number
char myLetter = 'D'; // Character
// Print variables
printf("%dn", myNum);
printf("%fn", myFloatNum);
printf("%cn", myLetter);

10. C Operators
Operators
 Operators are used to perform operations on
variables and values.
 Example: int myNum = 100 + 50;
 In the example above, we use the + operator to add
together two values.

11. C divides the operators into the following groups:
 Arithmetic operators
 Assignment operators
 Comparison operators
 Logical operators
 Bitwise operators
C Operators

12. C Operators

13. #include <stdio.h>
int main() {
int a = 10, b = 3;
printf("Addition: %d + %d = %dn", a, b, a + b);
printf("Subtraction: %d - %d = %dn", a, b, a - b);
printf("Multiplication: %d * %d = %dn", a, b, a * b);
printf("Division: %d / %d = %dn", a, b, a / b);
printf("Modulus: %d %% %d = %dn", a, b, a % b);
return 0;
}

14. Assignment Operators
 Assignment operators are used to assign values to
variables.
 In the example below, we use the assignment operator (=)
to assign the value 10 to a variable called x:
 int x = 10;

16. #include <stdio.h>
int main() {
int a = 10;
printf("Initial value: a = %dn", a);
a += 5;
printf("After a += 5: a = %dn", a);
a -= 3;
printf("After a -= 3: a = %dn", a);
a *= 2;
printf("After a *= 2: a = %dn", a);
a /= 4;
printf("After a /= 4: a = %dn", a);
a %= 5;
printf("After a %%= 5: a = %dn", a);
return 0;
}

17. Comparison Operators
 Comparison operators are used to compare two values (or variables).
This is important in programming, because it helps us to find answers
and make decisions.
 The return value of a comparison is either 1 or 0, which means true (1)
or false (0). These values are known as Boolean values.
 In the following example, we use the greater than operator (>) to find
out if 5 is greater than 3:
int x = 5;
int y = 3;
printf("%d", x > y); // returns 1 (true) because 5 is greater
than 3

19. #include <stdio.h>
int main() {
int a = 10, b = 20;
printf("a == b: %dn", a == b);
printf("a != b: %dn", a != b);
printf("a > b: %dn", a > b);
printf("a < b: %dn", a < b);
printf("a >= b: %dn", a >= b);
printf("a <= b: %dn", a <= b);
return 0;
}

20. Logical Operators
 You can also test for true or false values with logical
operators.
 Logical operators are used to determine the logic between
variables or values, by combining multiple conditions:

21. C If ... Else
 Conditions and If Statements
 You have already learned that C supports the usual
logical conditions from mathematics:
 Less than: a < b
 Less than or equal to: a <= b
 Greater than: a > b
 Greater than or equal to: a >= b
 Equal to a == b
 Not Equal to: a != b

22. C has the following conditional statements:
 Use if to specify a block of code to be executed, if a
specified condition is true
 Use else to specify a block of code to be executed,
if the same condition is false
 Use else if to specify a new condition to test, if
the first condition is false
 Use switch to specify many alternative blocks of
code to be executed
C If ... Else

23. C If ... Else
Syntax
if (condition) {
// block of code to be executed if the condition is true
}
if (20 > 18) {
printf("20 is greater than 18");
}

24. C If ... Else
Syntax
if (condition) {
// block of code to be executed if the condition is true
} else {
// block of code to be executed if the condition is false
}
int time = 20;
if (time < 18) {
printf("Good day.");
} else {
printf("Good evening.");
}// Outputs "Good evening."

25. C If ... Else
Syntax
if (condition1) {
// block of code to be executed if condition1 is true
} else if (condition2) {
// block of code to be executed if the condition1 is false and
condition2 is true
} else {
// block of code to be executed if the condition1 is false and
condition2 is false
}

26. C If ... Else
int time = 22;
if (time < 10) {
printf("Good morning.");
} else if (time < 20) {
printf("Good day.");
} else {
printf("Good evening.");
}
// Outputs "Good evening."

27. C Switch
Switch Statement
• Instead of writing many if..else statements, you can use
the switch statement.
• The switch statement selects one of many code blocks to
be executed:

28. C Switch
switch (expression) {
case x:
// code block
break;
case y:
// code block
break;
default:
// code block
}

29. C Switch
• The switch expression is evaluated once
• The value of the expression is compared with the values
of each case
• If there is a match, the associated block of code is
executed
• The break statement breaks out of the switch block
and stops the execution
• The default statement is optional, and specifies some
code to run if there is no case match

30. C Switch
switch (expression) {
case x:
// code block
break;
case y:
// code block
break;
default:
// code block
}

31. #include <stdio.h>
int main() {
int day = 4;
switch (day) {
case 1:
printf("Monday");
break;
case 2:
printf("Tuesday");
break;
case 3:
printf("Wednesday");
break;
case 4:
printf("Thursday");
break;
case 5:
printf("Friday");
break;
case 6:
printf("Saturday");
break;
case 7:
printf("Sunday");
break;
}
return 0;
}`

32. For Loop
• The for loop in C is a control flow statement that allows
you to iterate over a block of code multiple times.
• It is especially useful when the number of iterations is
known beforehand.
• Syntax of for Loop:
• for (initialization; condition; increment/decrement)
{
// Code to be executed
}

33. For Loop
 Initialization: This step is executed once before the loop
starts. It usually initializes a loop counter.
 Condition: This is checked before each iteration. If it's
true, the loop body executes; if it's false, the loop stops.
 Update: This is executed after each iteration and typically
increments or decrements the loop counter.

34. For Loop
#include <stdio.h>
int main()
{
for (int i = 1; i <= 5; i++)
{ printf("i = %dn", i);
}
return 0;
}

36. Problem 1
#include <stdio.h>
int main() {
for (int i = 100; i >= 0; i =i- 10) {
printf("%dn", i);
}
return 0;
}

37. Problem 2
#include <stdio.h>
int main() {
int sum = 0;
for (int i = 30; i <= 120; i++) {
if (i % 3 == 0 && i % 5 == 0) {
sum += i;
}
}
printf("Summation of numbers divisible by 3 and 5 between 30 and 120 is: %dn", sum);
return 0;

38. Nested Loop
 It is also possible to place a loop inside another loop. This
is called a nested loop.
 The "inner loop" will be executed one time for each
iteration of the "outer loop":

39. Nested Lopp
for (initialization; condition;
increment/decrement)
{
// Outer loop code
for (initialization; condition;
increment/decrement)
{
// Inner loop code
}
}

40. Nested Loop
#include<stdio.h>
int main(){
int i, j;
// Outer loop
for (i = 1; i <= 2; ++i) {
printf("Outer: %dn", i); // Executes 2 times
// Inner loop
for (j = 1; j <= 3; ++j) {
printf(" Inner: %dn", j); // Executes 6 times (2 * 3)
}
}
}

41. While Loop
The while loop loops through a block of code as long as a
specified condition is true:
while (condition) {
// code block to be executed
}

42. C++ While Loop
int i = 0;
while (i < 5) {
printf("%dn", i);
i++;
}

43. The Do/While Loop
• The do/while loop is a variant of the while loop.
• This loop will execute the code block once, before
checking if the condition is true, then it will repeat the
loop as long as the condition is true.
• do {
// code block to be executed
}
while (condition);

44. The Do/While Loop
int i = 0;
do {
printf("%dn", i);
i++;
}
while (i < 5);

45. C Break
• You have already seen the break statement used in an
earlier chapter of this tutorial. It was used to "jump out"
of a switch statement.
• The break statement can also be used to jump out of a
loop.
• This example jumps out of the loop when i is equal to 4:
• int i;
for (i = 0; i < 10; i++) {
if (i == 4) {
break;
}
printf("%dn", i);
}

46. Continue
The continue statement breaks one iteration (in the loop), if a
specified condition occurs, and continues with the next
iteration in the loop.
This example skips the value of 4:
#include <stdio.h>
int main() {
int i;
for (i = 0; i < 10; i++) {
if (i == 4) {
continue;
}
printf("%dn", i);
}
return 0;
}