C Programming Notes PDF

# C Programming - C programming language was developed at AT&T's Bell Laboratories of USA in 1972 by Dennis Ritchie. - Initially, C language was developed to be used in UNIX operating systems. - C programming language is a middle-level because it has both a relatively faster programming efficiency a...

# C Programming - C programming language was developed at AT&T's Bell Laboratories of USA in 1972 by Dennis Ritchie. - Initially, C language was developed to be used in UNIX operating systems. - C programming language is a middle-level because it has both a relatively faster programming efficiency and relatively good machine efficiency i.e., faster execution. ## Structures of C - Structure means to break a program into parts or blocks so that it may be easy to understand. We break the program into parts using functions, data-types, syntax, etc. ## Interpreter VS Compiler - A high language is one that is understandable by humans and is called as Source Code. - However, a computer does not understand high-level language, It only knows binary or machine code. - Both compilers and interpreters use to convert high-level language into machine code or binary code. | Interpreter | Compiler | | ------------------------------------------- | ----------------------------------------------------------------------------- | | Translates program one statement at a time. | Scans the entire program and translates it as 'a whole' into machine code. | | Takes less amount of time analyze the source code. The overall execution time is slower than compiler. | Takes a large amount of time to analyze the source code. Overall execution time is faster than interpreters. | | No object code is generated, hence are memory efficient. | Generates object code, which further requires linking, hence requires more memory. | | Programming languages like JavaScript, Python, Ruby use interpreters. | Programming languages like C, C++, Java use compilers. | ## The form of C programming - A C program is divided into six sections. - Documentation, Link, Definition, Global declaration, Main() function, Sub programs. - While the main function section is compulsory, the rest are optional in the structure of C program. - Every C program will have one or more functions and there is one mandatory function which is called main(). - This function is prefixed with keyword int. ## Library and Linking - A library is a collection of pre-compiled object files that can be linked to programs. - Library are typically stored as special archive with extension 'a'. - Linking refers to the creation of a single executable file from multiple object files. It is common that the linker will complain about undefined functions. ## To write the first C program ``` #include <stdio.h> int main() { printf("Hello World"); return 0; } ``` - `#include <stdio.h>` includes the standard input output library functions. The `printf()` function is defined in `stdio.h`. - The `main` function is the entry point of every program in C language. Here it is `int main()` - `printf()` function is used to print data on the console. It just displays the message. - **To compile C program- Ctrl + F9** - **To run C program- Alt + F9** # Algorithm - Algorithm is a simple English statement which provide step by step process for the given problem /program/question. - For example, an algorithm to find if given number is even or odd. 1. Start. 2. Accept a number. 3. Divide number by 2 and find remainder. 4. Check if remainder is zero or not. 5. If remainder is zero (i.e. n % 2 == 0) print given number is even. 6. Else print given number is odd. 7. Stop. ## Q.i. Write an algorithm to print addition of two numbers. 1. Start. 2. Accept two numbers. 3. Perform operation nl + n2. 4. Print result. 5. Stop. ## π. Write an algorithm to find area of circle. 1. Start. 2. Accept radius value. 3. Find the area using formula `3.14 x radius^2`. 4. Print result. 5. Stop. ## 1. Write an algorithm to find net salary (Net salary = Basic + ta + da) (ta = 20 % of basic, da = 40 % of basic) 1. Start. 2. Accept value of basic salary. 3. Calculate ta using formula, `ta = 20 x basic / 100`. 4. Calculate da using formula, `da = 40 x basic / 100`. 5. Add values of ta and da into basic. 6. Print result. 7. Stop. ## iv. Write an algorithm to find area of a rectangle. 1. Start. 2. Accept values of sides of a rectangle. 3. Calculate area using formula `length x width`. 4. Print result. 5. Stop. ## v. Write an algorithm to find area of a triangle. 1. Start. 2. Accept values of base and height of triangle. 3. Calculate area using formula, `area = 1/2 x b x h`. 4. Print result. 5. Stop. ## vi. Write an algorithm to find the area of square. 1. Start. 2. Accept value of side of a square. 3. Multiply the value by itself to get the area of square. 4. Print result. 5. Stop. ## vii. Write an algorithm to find square of a number. 1. Start. 2. Accept a number. 3. Multiply the number by itself. 4. Print result. 5. Stop. # Flow-Chart - It is a pictorial or diagrammatic representation of an algorithm. - Symbols used in Flow chart. 1. **start/stop symbol** 2. **input/output symbol** 3. **processing symbol** 4. **decision symbol** 5. **flowline symbol** 6. **connector symbol** ## Q.i. Draw a flowchart to print addition of two integer numbers. - **Algorithm:** 1. Accept two numbers nl, n2. 2. Perform operation `nl + n2`. 3. Print result. - **Flowchart:** ``` start ↓ Read "num1","num2" ↓ sum = num1 + num2 ↓ Print sum ↓ end ``` ## (ii) Draw a flowchart to print given number is odd or even. - **Flowchart:** ``` start ↓ Accept "nl" ↓ if n%2==0 ↓ Yes ↓ Print Even ↓ Stop No ↓ Print Odd ↓ Stop ``` ## (iii) Draw a flowchart to print if given number is prime or not. - **Algorithm:** 1. Start. 2. Read number n 3. Check the number is not divisible by 2 to n/2 - 1 4. If (iii) is true print given number is prime. else print given number is not prime. 5. Stop. - **Flowchart:** ``` Start ↓ Read "n", i = 2 ↓ if i == n ↓ Yes ↓ Print prime No ↓ if n / i == 0 ↓ Yes ↓ Print not a prime No ↓ i = i + 1 ↓ Stop ``` ## (iv) Draw a flowchart to print print largest number among given two number. - **Algorithm:** 1. Start. 2. Accept two number `nl, n2`. 3. Check if `nl > n2`, print `nl` is largest. else, check `n1 == n2`, print `n1` and `n2` are equal. else, print `n2` is largest. 4. Stop. - **Flowchart:** ``` Start ↓ Accept two numbers "nl", "n2" ↓ if nl > n2 ↓ Yes ↓ Print "nl is largest" ↓ Stop No ↓ if "n1 == n2 ↓ Yes ↓ Print "n1 and n2 equal ↓ No ↓ Print "n2 is largest ↓ Stop ``` ## v. Draw a flowchart to find largest number among three numbers. - **Flowchart:** ``` Start ↓ Input A, B, C ↓ If A > B ↓ Yes ↓ If A > C ↓ Yes ↓ Print "A is greater" ↓ Stop No ↓ If B > C ↓ Yes ↓ Print "B is greater" ↓ Stop No ↓ Print "C is greater" ↓ Stop ``` # Variable - Variable is a name of memory location. Its value can be changed. It is used to store data/information. - It is non-static. - A variable is character, i.e., nothing but information (alphabet, digit, symbol). ## Syntax: `<datatype> <variable1>, <variable2>,…;` ## Key Word: - A reserved word we cannot use for our purpose, i.e., cannot use as a variable. - Those keywords are: - break - case - char - const - continue - default - unsigned - do - double - else - enum - float - for - void - goto - if - int - long - return - short - while - signed - sizeof - static - struct - switch - typedef - …etc. - For example, while declaring variable, we can’t use `int char;` because `char` is datatype keyword. ## Constants - A constant is a value that cannot be changed in a program. - **Primary Constants:** - Integer, float, character are called as primary constants. - **Secondary Constants:** - array, structure, pointers, enum, etc. are called as secondary constants. ## Character Set - A character denotes any alphabet, digit or special symbol used to represent information. - Valid character set in C: - **Alphabets:** - A, B, C, …, Y, Z, a, b, c, …, y, z - **Digits:** - 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 - **Special Symbols:** - `* ! @ # $ % ^ & * ( ) - = + < > { } [ ] ; : " ? / ` ## Datatypes - **Basic datatypes:** Primary / Primitive datatypes - **Derived datatypes:** Secondary (union, structure, array, etc.) - **Enumerative datatypes:** Enums - **Void datatypes:** empty value / Nothing ## Integer Datatype - Integers are whole numbers, excluding decimal values. - Integer datatype occupies 2 bytes (32 bit) and 4 byte (64 bit size) of memory to store an integer value. - The range of 2 byte memory can hold any value between -32768 and 32767. - The range of 4 byte memory can hold any value between -2147483648 to 2147483647. - **Example:** ``` int age = 10; ``` - In this example, the variable named `age` would be defined as an integer and assigned the value of 10. ## Character Datatype - Character datatype stores character in fixed length field. Character can be a number, letter, symbol. - The size of both signed and unsigned character is `1 byte`. - **Example:** ``` char ch = 'a'; ``` - Here `ch` is variable and value assigned to it is 'a'. ## Floating Datatype - Float is a floating point number which has a decimal number place. It is used when more precision is needed. - **For example:** ``` float pi = 3.14; ``` - Here `pi` is variable of type `float` and assigned value is `3.14`. ## Operators and Expressions - Operators are one of the features in C which has symbols that can be used to perform mathematical, relational, bitwise, conditional, or logical manipulations. - The C programming language has a lot of built-in operators to perform various tasks as per need of the program. ## (1) Arithmetic Operators: - Arithmetic operators are used to perform common mathematical operations. | Operator | Name | Description | | -------- | -------------- | ---------------------------------------------------------------------------------------------------------- | | + | Addition | Adds together two values | | - | Subtraction | Subtract one value from another | | * | Multiplication | Multiplies two values. | | / | Division | Divides one value by another | | % | Modulus | Returns the division remainder. | | ++ | Increment | Increases the value of variable by 1 | | -- | Decrement | Decreases the value of variable by 1 | ## (2) Relational Operators (Comparison Operators) - It checks the relationship between two operands. - If the given relation is true, it will return 1 and if the relation is false, then it will return 0. | Operator | Name | Description | | -------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | == | Equal to | Check if the values are equal. | | != | Not equal | Check if the values are not equal. | | > | Greater than | Check if the first value is greater than second. | | < | Less than | Check if the first value is less than second. | | >= | Greater than or equal to | Check if the first value is greater than or equals to second value. | | <= | less than or equal to | Check if the first value is less than or equals to second value. | - The return value of comparison is either one `1` or `0`, which means true (1) or false (0) These values are known as Boolean values. ## (3) Logical Operators - Logical operators are used to test more than one condition in a program. - These logical operators are: | Operator | Name | Description | | -------- | -------- | ------------------------------------------------------------------------------------------- | | && | AND | Check if all conditions are true. | | || | OR | Check if one of the conditions is true. | | ! | NOT | Reverse the result. (return 0 if result is 1) | ## (4) Increment / Decrement Operator ### (i) Increment: - Increment operators are the unary operators used to increment or add 1 to the operand value. - The increment operand is denoted by the double plus symbol `++`. - If we use the increment operator as a prefix, it is called pre-increment. - The pre-increment operator is used to increase the original value of operand by 1 before assigning it to the expression. - **Syntax:** ``` x = ++A; ``` - The value of operand `A` is increased by `1` and then new value is assigned to variable. - If we use the increment operator as postfix, it is called as post-increment. - The post-increment operator is used to increase the original value by `1` after assigning it to the expression. - **Syntax:** ``` x = A++; ``` - The value of operand `A` is assigned to the variable. After that, the value `A` is incremented by `1`. ### (ii) Decrement - Decrement operators are unary operator used to decrease the original value of operand by `1`. - The decrement operator is denoted by double minus symbol `--`. - If we use decrement operator as a prefix, it is called pre-decrement. - The pre-decrement operator is used to assign decrease the operand value by `1` before assigning it to the mathematical expression. - (Simply, new value is assigned to variable). - **Syntax:** ``` B = --A; ``` - The value of operand `A` is decreased by `1`, and then the new value is assigned to variable `B`. - If we use decrement operator as a postfix, it is called post-decrement. - The post-decrement operator is used to decrease the value of operand by `1` after assigning it to the expression. - (Simply, it assign the value, then decrease the operand.) - **Syntax:** ``` B = A--; ``` - In the above example, the value of operand `A` is assigned to the variable `B`, and then the value of `A` is decreased by `1`. ## (5) Bitwise Operator - Bitwise operators are the operators which work on bits and perform the bit by bit operation. - Mathematical operators like addition, subtraction, multiplication, division, etc. are converted to bit level which makes processing faster and easier to implement and compilation of a program.