Data Types:
In C, data types specify the type of data that a variable can hold. The basic data types in C are:
int: Integer data type, used for whole numbers.
int age = 25;
short int: Typically 16 bits.
int: Minimum 16 bits, usually 32 bits.
long int: Minimum 32 bits.
long long int: Minimum 64 bits.
long long int bigNumber = 1234567890123456LL;
float: Floa ng-point data type, used for numbers with decimal points.
float price = 19.99;
double: Double-precision floa ng-point data type, provides more precision than float.
double pi = 3.14159265359;
float: 32-bit floa ng-point.
double: 64-bit double-precision floa ng-point.
long double: Extended precision.
double price = 99.99;
char: Character data type, used for single characters.
char grade = 'A';
char: Typically 8 bits.
signed char: Can represent both posi ve and nega ve values.
unsigned char: Represents only non-nega ve values.
_Bool: Boolean data type, represents true or false values.
_Bool isPassed = 1; // true
void: Represents the absence of a type or no value.
void func onWithoutReturnValue() {
// Some code here
Variables:
Variables are used to store and manipulate data in a program. They must be declared before
use, specifying their data type.
int main() {
int x; // Declara on
x = 10; // Ini aliza on
return 0;
}
Constants:
Constants are values that do not change during the execu on of a program. They can be
defined using the const keyword.
const float PI = 3.1415;
Literals:
Literals are constant values that are used directly in the program. For example:
Integer literals: 10, 20
Floa ng-point literals: 3.14, 2.0
Character literals: 'A', 'b'
Storage Classes:
Storage classes in C determine the scope and life me of variables. The main storage classes
are:
auto: The default storage class for local variables. The variable is automa cally created and
destroyed.
register: Similar to auto, but suggests the compiler to store the variable in a register for faster
access.
sta c: The variable retains its value between func on calls. It has a file scope if declared
outside a func on.
extern: Informs the compiler that the variable is defined elsewhere. Used for global variables.
Operators:
Operators in C are symbols that perform opera ons on variables and values. They can be
categorized as:
Arithme c Operators: +, -, *, /, %
int result = 10 + 5; // result is 15
Rela onal Operators: ==, !=, <, >, <=, >=
int x = 5, y = 10;
if (x < y) {
// Code executes if x is less than y
}
Logical Operators: && (AND), || (OR), ! (NOT)
int a = 1, b = 0;
if (a && b) {
// Code executes if both a and b are true
}
Assignment Operators: =, +=, -=, *=, /=
x += 5; // Equivalent to x = x + 5
Increment/Decrement Operators: ++, --
int count = 10;
count++; // Increment by 1
Bitwise Operators: &, |, ^, <<, >>
int a = 5, b = 3;
int result = a & b; // Bitwise AND
Condi onal (Ternary) Operator: condi on ? expr1 : expr2
int max = (a > b) ? a : b; // If a is greater than b, max is a; otherwise, max is b.
sizeof Operator: Returns the size of a data type or object.
int size = sizeof(int); // size is the size of an integer in bytes
Programming ques ons:
1. Write a program to swap the values of two variables without using a third variable.
#include <stdio.h>
int main() {
int a = 5, b = 10;
prin ("Before Swap: a = %d, b = %d\n", a, b);
a = a + b;
b = a - b;
a = a - b;
prin ("A er Swap: a = %d, b = %d\n", a, b);
return 0;
}
2. Write a program to check if a given integer is even or odd
#include <stdio.h>
int main() {
int num;
prin ("Enter an integer: ");
scanf("%d", &num);
if (num % 2 == 0)
prin ("%d is even.\n", num);
else
prin ("%d is odd.\n", num);
return 0;
}
3. Write a program to calculate the area of a circle using the radius.
#include <stdio.h>
int main() {
float radius, area;
prin ("Enter the radius of the circle: ");
scanf("%f", &radius);
area = 3.14 * radius * radius;
prin ("Area of the circle: %f\n", area);
return 0;
}
4. Declare a constant named PI and a variable named radius. Calculate the circumference
using the formula: circumference = 2 * PI * radius.
#include <stdio.h>
int main() {
const float PI = 3.14;
float radius, circumference;
prin ("Enter the radius of the circle: ");
scanf("%f", &radius);
circumference = 2 * PI * radius;
prin ("Circumference of the circle: %f\n", circumference);
return 0;
}
5. Write a program to perform bitwise AND, OR, and XOR opera ons on two integers.
#include <stdio.h>
int main() {
int a = 12, b = 25;
prin ("Bitwise AND: %d\n", a & b);
prin ("Bitwise OR: %d\n", a | b);
prin ("Bitwise XOR: %d\n", a ^ b);
return 0;
}
6. Write a program to check whether a given year is a leap year or not.
#include <stdio.h>
int main() {
int year;
prin ("Enter a year: ");
scanf("%d", &year);
if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))
prin ("%d is a leap year.\n", year);
else
prin ("%d is not a leap year.\n", year);
return 0;
}
7. Write a program to calculate the sum of digits of a posi ve integer.
#include <stdio.h>
int main() {
int num, sum = 0;
prin ("Enter a posi ve integer: ");
scanf("%d", &num);
while (num > 0) {
sum += num % 10;
num /= 10;
}
prin ("Sum of digits: %d\n", sum);
return 0;
}
8. Write a program to calculate the factorial of a given number.
#include <stdio.h>
int factorial(int n) {
if (n == 0 || n == 1)
return 1;
else
return n * factorial(n - 1);
}
int main() {
int num;
prin ("Enter a number: ");
scanf("%d", &num);
prin ("Factorial of %d: %d\n", num, factorial(num));
return 0;
}
9. Write a program that ini alizes an array of integers and finds the sum and average of
its elements.
#include <stdio.h>
int main() {
int numbers[] = {2, 4, 6, 8, 10};
int sum = 0, size = sizeof(numbers) / sizeof(numbers[0]);
for (int i = 0; i < size; ++i) {
sum += numbers[i];
}
float average = (float)sum / size;
prin ("Sum: %d\n", sum);
prin ("Average: %f\n", average);
return 0;
}
10. Write a program to simulate a basic login system using logical operators.
#include <stdio.h>
int main() {
char username[] = "user123";
char password[] = "pass456";
char inputUsername[20];
char inputPassword[20];
prin ("Enter username: ");
scanf("%s", inputUsername);
prin ("Enter password: ");
scanf("%s", inputPassword);
if (strcmp(username, inputUsername) == 0 && strcmp(password, inputPassword) ==
0)
prin ("Login successful!\n");
else
prin ("Login failed!\n");
return 0;
}
11. Write a program to find the maximum of two numbers using the condi onal (ternary)
operator.
#include <stdio.h>
int main() {
int a, b;
prin ("Enter two numbers: ");
scanf("%d %d", &a, &b);
int max = (a > b) ? a : b;
prin ("Maximum: %d\n", max);
return 0;
}
12. Write a program to find the length of a string without using the `strlen` func on.
#include <stdio.h>
int stringLength(char str[]) {
int length = 0;
while (str[length] != '\0') {
length++;
}
return length;
}
int main() {
char text[] = "Hello, World!";
prin ("Length of the string: %d\n", stringLength(text));
return 0;
}
13. Write a program to le -shi and right-shi an integer by a specified number of
posi ons.
#include <stdio.h>
int main() {
int num, shi ;
prin ("Enter an integer: ");
scanf("%d", &num);
prin ("Enter the number of posi ons to shi : ");
scanf("%d", &shi );
prin ("Le -shi ed result: %d\n", num << shi );
prin ("Right-shi ed result: %d\n", num >> shi );
return 0;
}
14. Define a structure called `Person` with a ributes `name` and `age`. Create an array of
persons and print their details.
#include <stdio.h>
struct Person {
char name[50];
int age;
};
int main() {
struct Person people[3] = {{"Alice", 25}, {"Bob", 30}, {"Charlie", 22}};
for (int i = 0; i < 3; ++i) {
prin ("Person %d: %s, %d years old\n", i + 1, people[i].name, people[i].age);
}
return 0;
}
15. Create a union called `Value` that can store either an integer or a float. Write a
program to demonstrate its usage.
#include <stdio.h>
union Value {
int intValue;
float floatValue;
};
int main() {
union Value data;
data.intValue = 10;
prin ("Integer Value: %d\n", data.intValue);
data.floatValue = 3.14;
prin ("Float Value: %f\n", data.floatValue);
return 0;
}
