C Programming PDF

# C Programming ## 1. What is a computer? - A computer is an electronic device that can accept and store information, process it, and give the desirable result on output. - It can also help us solve various problems. ## 2. What is Programming? - Programming is a process for writing code to const...

# C Programming ## 1. What is a computer? - A computer is an electronic device that can accept and store information, process it, and give the desirable result on output. - It can also help us solve various problems. ## 2. What is Programming? - Programming is a process for writing code to construct an application and designing and building an executable computer program. ## 3. What is C? - C is a general-purpose, high-level programming language that is the mother of all languages. - C is called a procedure-oriented programming language (POP). ## 4. What is a Compiler? - A compiler is a computer program that translates computer code written in one programming language to another programming language. - It converts `.i` to `.obj` files. ## 5. Why are Header Files Used? - Used to define all the functions, variables contained in any function library. - A file where some predefined functions work. ## 6. Why is `#` used in header files? - The hash symbol helps the compiler load the header files that are needed for compilation of the whole program. - It is a preprocessor. ## 7. Who Developed C Language? - Dennis Ritchie at Bell Labs (USA), in 1972. ## 8. What is an Operating System? - System software that performs process management, file management, memory management. - Acts as a manager of the computer system. - Examples: Windows 7, Windows 8, Linux, Mac-OS ## 9. Why is Semicolon `(;)` used? - To terminate the statement. ## 10. Why are `{}` used? - To make a complete block. ## 11. Why is the `main()` Function Used in C Programs? - It is the core of every program. - It contains instructions that tell the computer to carry out whatever task the program is designed to do. ## 12. What is an Algorithm? - A way to write mathematical and logical problems step-by-step. - Helps the computer analyze. - Algorithms are universal. - Example: Algorithm of Series. | Step | Operation | |:---:|:---| | 1 | `x = 1` | | 2 | `Print(x)` | | 3 | `x = x + 1` | | 4 | `if(x < 11) goto Step 2;` | | 5 | `Stop;` | ## 13. What is a Flowchart? - A graphical view of an algorithm. - Called a flowchart. - Helps reduce program-making time. - Reduces errors in time. ### Flowchart Symbols | Symbol | Description | |:---|:---| | 🗲 | Starting/Ending Box | | 🗭 | Input/Output Box | | 🗬 | Processing Box | | 🗮 | Decision Box | | 🗶 | Flow Line | ## 14. What is an Operand? - Data or a variable on which the operation is performed. - Called an operand. ## 15. What is a Data Type? - A type of data used in the program. - Defines the amount of storage area allocated to variables. - Examples: | Data Type | Size (bytes) | |:---|:---| | `int` | 2 | | `char` | 1 | | `float` | 4 | | `double` | 8 | ## 16. What are the Types of Operators? - Arithmetic operators (+, -, *, /, %) - Relational operators (==, !=, <, >, <=, >=) - Logical operators (&&, ||, !) - Bitwise operators (&, |, ^, ~, >>, <<) - Conditional operators (?) - Increment/Decrement operators (++ and --) ## 17. What is a Local Variable? - A variable defined inside a block. - Called a local variable. ## 18. What is a Global Variable? - Declared outside any function and can be used in any function in the program. ## 19. What is an Operator? - Allows performing different kinds of operations on operands. - Special symbols that perform operations on one or more operands. ## 20. What is a Keyword? - Word that is predefined in the library. - A *keyword* is predefined. - Cannot be used as a variable. ## 21. What is a Variable? - Name of a storage area used to store data or information. ## 22. What is a Predefined Function? - A function predefined in the library. - Also called a *library function*. - Examples: `Printf()`, `Scanf()`, `getch()`, `clrscr()`, etc. ## 23. What is `Printf()`? - Predefined function used to *print* data or information, outputting results on to the output screen. - Defined inside *stdio.h* header file. ## 24. What is `Scanf()`? - Predefined function used to assign values. - Defined inside *stdio.h* header file. ## 25. What is `clcrscr()`? - Predefined function that clears the previous output screen. - Defined inside *conio.h* header file. ## 26. What is `getch()`? - Predefined function that holds the output screen. - Defined inside *conio.h* header file. ## 27. What is `void`? - A keyword. - Meaning: empty. ## 28. What are the Full Names of *conio* and *stdio*? - **stdio**: Standard input output. - **conio**: Console input output. ## 29. Execution of a Program - A simplified diagram: **Processor** - Set of registers & instruction register. - Memory unit. - Control Unit - ALU (Arithmetic Logic Unit) - Hard Disk - Program is saved in the hard disk and double-clicked to load it into the RAM. - Instruction is passed to the memory unit in the form of a register. - Control unit decodes the instruction and sends it to the ALU. - ALU performs the arithmetic and logical calculations, and the instruction is executed. ## 30. How to Make a Software? - Simplified diagram, steps: - Source file has the `.c` extension. - Preprocessor loads the header files and makes a `.obj` file. - Compiler converts the `.obj` file to an object file. - Linker connects the object files and library files, and creates a `.exe` file. ## 31. What are Tokens? - Basic building blocks in the C language. - Constructed together to write a C program. - Smallest individual units in a C program. ## 32. Structure of C 1. **Header File** 2. **Main Function** 3. **Open Curly Braces (`{`)** 4. **Logical Variable Declaration** 5. **Input the Program** 6. **Process (Arithmetic & Logical unit)** 7. **Output of the Program** 8. **End** 9. **Close Curly Braces (`}`)** ## 33. Data Types - **Primary data types**: `char`, `int`, `float`, `double`. - **Derived data types**: `arrays`, `structures`, `unions`, `pointers`, `enums`. - **User-defined data types**: `structures`, `unions`, `enums`. ### Primary Data Types | Data Type | Size (bytes) | Example | |:---|:---|:---| | `char` | 1 | `a`, `b`, `c` | | `int` | 2 | `1`, `2`, `3` | | `float` | 4 | `1.5`, `7.8`, `12.04671` | | `double` | 8 | `1.5`, `7.8`, `12.04671` | - **String**: a group of `char` - **`clrscr()`**: to clear screen - **`getch()`**: to hold screen - **`stdio.h`**: standard input/output functions (`Printf()`, `Scanf()`, etc.) - **`conio.h`**: console input/output functions (`clrscr()`, `getch()`, etc.) ## 34. Sum of Two Numbers ```c #include <stdio.h> #include <conio.h> void main() { int a, b, c; clrscr(); printf("Enter two numbers: "); scanf("%d%d", &a, &b); c = a + b; printf("Sum = %d", c); getch(); } ``` ## 35. Group of Characters ```c #include <stdio.h> #include <conio.h> void main() { char a[20]; clrscr(); printf("Enter name: "); scanf("%s", a); printf("Name: %s", a); getch(); } ``` ## 36. Swap Two Numbers Without Third Variable ```c #include <stdio.h> #include <conio.h> void main() { int a, b; clrscr(); printf("Enter two numbers: "); scanf("%d%d", &a, &b); // Single line swap a = a + b; b = a - b; a = a - b; printf("%d %d", a, b); getch(); } ``` ## 37. Operators - Operators allow performing different types of operations on operands. - Types of operators: - Increment/Decrement - Arithmetic - Relational - Logical - Bitwise - Conditional ### Increment/Decrement Operators - **Unary plus (`+`)**: Increases the value by 1. - **Unary minus (`-`)**: Decreases the value by 1. - **Increment (`++`)**: Increases the value by 1. - **Pre-increment**: Increases the value before assigning it. - **Post-increment**: Increases the value after assigning it. - **Decrement (`--`)**: Decreases the value by 1. - **Pre-decrement**: Decreases the value before assigning it. - **Post-decrement**: Decreases the value after assigning it. ### How to Solve Expressions with Increment/Decrement Operators 1. Count the number of pre-increment and pre-decrement operators in the expression. 2. Perform each increment/decrement operation for the appropriate number of times on the right-hand side of the expression. 3. Update the values on all operands based on the results of the increment/decrement operations. 4. Count the number of post-increment and post-decrement operators in the expression. 5. Perform any remaining increment/decrement operations. ## 38. Arithmetic Operators - **Addition (`+`)**: Adds two operands. - **Subtraction (`-`)**: Subtracts the second operand from the first operand. - **Multiplication (`*`)**: Multiplies two operands. - **Division (`/`)**: Divides the first operand by the second operand. - **Modulo (`%`)**: Returns the remainder of the division operation. ## 39. Finding the Modulo Value ```c #include <stdio.h> #include <conio.h> void main() { int a, b, c; clrscr(); a = 10; b = 5; c = a%b; printf("The modulo is %d", c); getch(); } ``` ## 40. Relational Operators - **Equals to (`==`)**: Checks if two operands are equal. - **Not equals to (`!=`)**: Checks if two operands are not equal. - **Less than (`<`)**: Checks if the first operand is less than the second operand. - **Greater than (`>`)**: Checks if the first operand is greater than the second operand. - **Less than or equals to (`<=`)**: Checks if the first operand is less than or equal to the second operand. - **Greater than or equal to (`>=`)**: Checks if the first operand is greater than or equal to the second operand. - Relational operators compare two variables. - Return a boolean value (true or false) after comparison. ## 41. Bitwise Operators - Perform operations on individual bits of integers. - Operators: - `&`: Bitwise AND. Returns 1 if both bits are 1, otherwise 0. - `|`: Bitwise OR. Returns 1 if at least one of the bits is 1, otherwise 0. - `^`: Bitwise XOR. Returns 1 if the bits are different, otherwise 0. - `~`: Bitwise NOT. Inverts the bits of an operand. - `>>`: Bitwise Right Shift. Shifts bits to the right. - `<<`: Bitwise Left Shift. Shifts bits to the left. ## 42. Logical Operators - Used to combine multiple conditions. - Operators: - **AND (`&&`)**: Returns true only if both the operands are true. - **OR (`||`)**: Returns true if at least one of the operands is true. - **NOT (`!`)**: Inverts the logical state of an operand. ## 43. Conditional Operators - **Ternary Operator (`? :`)**: A shorthand for an `if-else` statement. ### Syntax ```c (condition) ? (expression1) : (expression2) ``` - If the *condition* is true, *expression1* is executed. - Otherwise, *expression2* is executed. ## 44. Decision Control Statements - Allow altering the flow of execution based on conditions. - Types: - **Simple if** - **if-else** - **if-else ladder** - **nested if** - **switch-case** ### Simple if Statement ```c if (condition) { // Code to execute if condition is true } ``` ### if-else Statement ```c if (condition) { // Code to execute if condition is true } else { // Code to execute if condition is false } ``` ### if-else Ladder ```c if (condition1) { // Code to execute if condition1 is true } else if (condition2) { // Code to execute if condition2 is true } else if (condition3) { // Code to execute if condition3 is true } else { // Code to execute if all conditions are false } ``` ### Nested if Statement ```c if (condition1) { if (condition2) { // Code to execute if both conditions are true } } ``` ### Switch-Case Statement ```c switch (expression) { case value1: // Code to execute if expression equals value1 break; case value2: // Code to execute if expression equals value2 break; // ... more cases default: // Code to execute if no match is found } ``` - `break`: Exits the `switch` block. - `default`: Optional. Executed when no other case matches. ## 45. Looping Statements - Used for repetitive execution of code. - Types: - **while** - **do-while** - **for** ### while Loop ```c while (condition) { // Code to execute as long as condition is true } ``` ### do-while Loop ```c do { // Code to execute } while (condition); ``` - The code in the `do` block is executed at least once, even if the *condition* is false. ### for Loop ```c for (initialization; condition; update) { // Code to execute } ``` - *Initialization* happens once before the loop starts. - The *condition* is checked before each iteration. - The *update* is executed after each iteration. ## 46. Nested for Loop - A `for` loop within another `for` loop. - Useful for iterating through multi-dimensional data structures. ## 47. Breaking from a Loop - **`break` statement**: Exits the current loop. - Useful for exiting the loop prematurely based on a specific condition. ## 48. Continuing a Loop - **`continue` statement**: Skips the rest of the current iteration and starts the next loop iteration. ## 49. Returning Values from a Function - **`return` keyword**: Used to return a value from a function. - Essential for functions with a *return type* other than `void`. ## 50. Functions - A block of code that performs a specific task. - Allows code reusability and modularity. ### Types of Functions - **Predefined functions**: Built-in functions provided by the C library. - Examples: `printf()`, `scanf()`, `strlen()`, `strcpy()`, etc. - **User-defined functions**: Functions created by the programmer. ### Function Declaration - Specifies the function's return type, name, and parameters. - Needed before the function is used in the code. - Example: ```c int add(int x, int y); // Declaration ``` ### Function Definition - Contains the actual code of the function. - Example: ```c int add(int x, int y) { int sum; sum = x + y; return sum; } ``` ### Function Call - Executes the code within a function. - Example: ```c int result = add(5, 10); // Function call ``` ### Function Definition with Return Type - Function definition includes a `return` statement to return a value. - Types: - **No return type**: `void`. - **With return type**: Specifies the type of data the function returns. ### Function Definition with Arguments - Function definition can accept arguments. - Arguments are passed to the function when it is called. - The function's arguments are known as *formal parameters* - The arguments passed inside the function call are called *actual parameters*. ### Function Definition with Return Type and Arguments - Provides a way to receive input and provide a specific output. ## 51. Arrays - Collection of elements of the same data type. - Allows storing multiple values under the same name. - Stored contiguously in memory. ### Array Properties - **Base address**: The memory address of the first element. - **Array index**: Starts from 0. - **Last index**: `(total size - 1)`. ### One-Dimensional Arrays - Stores data in a single row. ### Multi-Dimensional Arrays - Stores data in multiple rows and columns. ## 52. Structure - Allows storing data of different data types under a single name. - Similar to a class in object-oriented programming. ### Structure Definition ```c struct struct_name { data_type variable_1; data_type variable_2; // ... more variables }; ``` ### Accessing Structure Members - Use the dot (`.`) operator. ### Structure Initialization - Can be done during declaration or later. ## 53. Union - A user-defined data type that allows storing different data types in a single shared memory location. - Only one member of a union can be active at any given time. ### Union Definition ```c union union_name { data_type member_1 ; data_type member_2; // ... more members }; ``` ### Union Properties - Size of the union is the size of the largest member. - Can only hold the value of the last member assigned to it. ## 54. Pointers - Variables that store memory addresses of other variables. - Provide a way to access and manipulate data directly in memory. ### Pointer Declaration - Use the `*` symbol. ### Assigning a Pointer - Use the `&` operator to get the address of a variable. ### Dereferencing a Pointer - Use the `*` operator to access the value stored at the address the pointer points to. ## 55. Pointer to Pointer - A pointer that holds the address of another pointer. - Useful for managing data structures like linked lists and trees. ## 56. Parameter Passing Methods - How arguments are passed from the calling function to the called function. - Two main methods: - **Call by Value**: Copies the values of the actual parameters to the formal parameters. Changes made inside the function do not affect the original values. - **Call by Reference (Address)**: Passes the memory addresses of the actual parameters to the formal parameters. Changes made inside the function affect the original values. ## 57. Recursion - A programming technique that allows a function to call itself within its own definition. - Useful for solving problems that can be broken down into similar subproblems. ## 58. Jumping Statements - Statements that alter the normal sequential flow of execution. - These statement "jump" to a different part of the code. - Types - **`goto`**: Unconditionally jumps to a specific label in the code. - **`break`**: Exits the current loop or `switch` statement. - **`continue`**: Skips the rest of the current loop iteration and begins the next iteration. - **`return`**: Returns a value from a function.