Computer enginneering 's note, Exercises of Computer Graphics

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LECTURE NOTE

on

PROGRAMMING IN “C”

COURSE CODE: MCA 101

By

Asst. Professor Mrs Etuari Oram Asst. Prof. Mr Bighnaraj Naik

SYLLABUS

Module –I

C Language Fundamentals. Character set, Identifiers, keyword, data types, Constants and variables, statements, expression, operators, precedence of operators, Input-output, Assignments, control structures decision making and branching.

Module -II

Arrays, Functions and Strings: Declaration, manipulation and String – handling

functions, monolithic vs. Modular programs, user defined vs. standard functions, formal vs. actual arguments, function – category, function prototypes, parameter passing, recursion, and storage classes: auto, extern, global, static.

Module –III

Pointers, Structures, Unions, File handling:

Pointer variable and its importance, pointer arithmetic, passing parameters, Declaration of structures, pointer to pointer, pointer to structure, pointer to function, union, dynamic memory allocation, file managements.

Lecture 13: String library functions Lecture 14: functions, categories Lecture 15: functions categories cont.. Lecture 16: Actual arguments and Formal arguments, call by value call by reference Lecture 17:local, global, static variable Lecture 18: monolithic vs modular programming, Storage classes Lecture 19:storage class cont.., pointer Lecture 20: pointer comparison, increment decrement Lecture 21: precedence level of pointer, pointer comparison Lecture 22: pointer to pointer, pointer to structure Lecture 23: pointer initialization, accessing elements Module: 3 Lecture 24: size of Structure in, array vs structure, array within structure Lecture 25: passing structure to function, Nested Structure Lecture 26: Union Lecture 27: nesting of unions, dynamic memory allocation Lecture 28: dynamic memory allocation conti… Lecture 29: dynamic array, file Lecture 30: file operation Lecture 31: file operation on string Lecture 32: Lecture 33:

Lecture Note: 1

Introduction to C C is a programming language developed at AT & T’s Bell Laboratories of USA in 1972. It was designed and written by a man named Dennis Ritchie. In the late seventies C began to replace the more familiar languages of that time like PL/I, ALGOL, etc ANSI C standard emerged in the early 1980s, this book was split into two titles: The original was still called Programming in C , and the title that covered ANSI C was called Programming in ANSI C. This was done because it took several years for the compiler vendors to release their ANSI C compilers and for them to become ubiquitous. It was initially designed for programming UNIX operating system. Now the software tool as well as the C compiler is written in C. Major parts of popular operating systems like Windows, UNIX, Linux is still written in C. This is because even today when it comes to performance (speed of execution) nothing beats C. Moreover, if one is to extend the operating system to work with new devices one needs to write device driver programs. These programs are exclusively written in C. C seems so popular is because it is reliable , simple and easy to use. often heard today is – “C has been already superceded by languages like C++, C# and Java. Program

Low level languages are machine level and assembly level language. In machine level language computer only understand digital numbers i.e. in the form of 0 and 1. So, instruction given to the computer is in the form binary digit, which is difficult to implement instruction in binary code. This type of program is not portable, difficult to maintain and also error prone. The assembly language is on other hand modified version of machine level language. Where instructions are given in English like word as ADD, SUM, MOV etc. It is easy to write and understand but not understand by the machine. So the translator used here is assembler to translate into machine level. Although language is bit easier, programmer has to know low level details related to low level language. In the assembly level language the data are stored in the computer register, which varies for different computer. Hence it is not portable. High level language: These languages are machine independent, means it is portable. The language in this category is Pascal, Cobol, Fortran etc. High level languages are understood by the machine. So it need to translate by the translator into machine level. A translator is software which is used to translate high level language as well as low level language in to machine level language. Three types of translator are there: Compiler Interpreter Assembler Compiler and interpreter are used to convert the high level language into machine level language. The program written in high level language is known as source program and the corresponding machine level language program is called as object program. Both compiler and interpreter perform the same task but there working is different. Compiler read the program at-a-time and searches the error and lists them. If the program is error free then it is converted into object program. When program size is large then compiler is preferred. Whereas interpreter read only one line of the source code and convert it to object code. If it check error, statement by statement and hence of take more time.

Integrated Development Environments (IDE) The process of editing, compiling, running, and debugging programs is often managed by a single integrated application known as an Integrated Development Environment, or IDE for short. An IDE is a windows-based program that allows us to easily manage large software programs, edit files in windows, and compile, link, run, and debug programs. On Mac OS X, CodeWarrior and Xcode are two IDEs that are used by many programmers. Under Windows, Microsoft Visual Studio is a good example of a popular IDE. Kylix is a popular IDE for developing applications under Linux. Most IDEs also support program development in several different programming languages in addition to C, such as C# and C++.

#include<stdio.h> tells the compiler to include information about the standard input/output library. It is also used in symbolic constant such as #define PI 3.14(value). The stdio.h (standard input output header file) contains definition &declaration of system defined function such as printf( ), scanf( ), pow( ) etc. Generally printf() function used to display and scanf() function used to read value Global Declaration: This is the section where variable are declared globally so that it can be access by all the functions used in the program. And it is generally declared outside the function : main() It is the user defined function and every function has one main() function from where actually program is started and it is encloses within the pair of curly braces. The main( ) function can be anywhere in the program but in general practice it is placed in the first position. Syntax : main() { …….. …….. …….. } The main( ) function return value when it declared by data type as int main( ) { return 0

The main function does not return any value when void (means null/empty) as void main(void ) or void main() { printf (“C language”); } Output: C language The program execution start with opening braces and end with closing brace. And in between the two braces declaration part as well as executable part is mentioned. And at the end of each line, the semi-colon is given which indicates statement termination. /First c program with return statement/** #include <stdio.h> int main (void) { printf ("welcome to c Programming language.\n"); return 0; } Output: welcome to c programming language. Steps for Compiling and executing the Programs A compiler is a software program that analyzes a program developed in a particular computer language and then translates it into a form that is suitable for execution

Step 3: When all the syntactic and semantic errors have been removed from the program, the compiler then proceeds to take each statement of the program and translate it into a “lower” form that is equivalent to assembly language program needed to perform the identical task. Step 4: After the program has been translated the next step in the compilation process is to translate the assembly language statements into actual machine instructions. The assembler takes each assembly language statement and converts it into a binary format known as object code , which is then written into another file on the system. This file has the same name as the source file under Unix, with the last letter an “ o ” ( for object ) instead of a “ c ”. Step 5: After the program has been translated into object code, it is ready to be linked. This process is once again performed automatically whenever the cc or gcc command is issued under Unix. The purpose of the linking phase is to get the program into a final form for execution on the computer. If the program uses other programs that were previously processed by the compiler, then during this phase the programs are linked together. Programs that are used from the system’s program library are also searched and linked together with the object program during this phase. The process of compiling and linking a program is often called building****. The final linked file, which is in an executable object code format, is stored in another file on the system, ready to be run or executed****. Under Unix, this file is called a.out by default. Under Windows, the executable file usually has the same name as the source file, with the c extension replaced by an exe extension.

Step 6: To subsequently execute the program, the command a.out has the effect of loading the program called a.out into the computer’s memory and initiating its execution. When the program is executed, each of the statements of the program is sequentially executed in turn. If the program requests any data from the user, known as input , the program temporarily suspends its execution so that the input can be entered. Or, the program might simply wait for an event , such as a mouse being clicked, to occur. Results that are displayed by the program, known as output , appear in a window, sometimes called the console. If the program does not produce the desired results, it is necessary to go back and reanalyze the program’s logic. This is known as the debugging phase , during which an attempt is made to remove all the known problems or bugs from the program. To do this, it will most

/* Simple program to add two numbers…………………….*/

#include <stdio.h> int main (void) { int v1, v2, sum; //v1,v2,sum are variables and int is data type declared v1 = 150; v2 = 25; sum = v1 + v2; printf ("The sum of %i and %i is= %i\n", v1, v2, sum); return 0; } Output: The sum of 150 and 25 is=

Lectu

re Note: 3

Character set A character denotes any alphabet, digit or special symbol used to represent information. Valid alphabets, numbers and special symbols allowed in C are

There are certain words reserved for doing specific task, these words are known as reserved word or keywords. These words are predefined and always written in lower case or small letter. These keywords cann’t be used as a variable name as it assigned with fixed meaning. Some examples are int, short, signed, unsigned, default, volatile, float, long, double, break, continue, typedef, static, do, for, union, return, while, do, extern, register, enum, case, goto, struct, char, auto, const etc. data types Data types refer to an extensive system used for declaring variables or functions of different types before its use. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted. The value of a variable can be changed any time. C has the following 4 types of data types basic built-in data types : int, float, double, char Enumeration data type: enum Derived data type : pointer, array, structure, union Void data type : void A variable declared to be of type int can be used to contain integral values only—that is, values that do not contain decimal places. A variable declared to be of type float can be used for storing floating- point numbers (values containing decimal places). The double type is the same as type float, only with roughly twice the precision. The char data type can be used to store a single character, such as the letter a , the digit character 6 , or a semicolon similarly A variable declared char can only store character type value. There are two types of type qualifier in c Size qualifier : short, long Sign qualifier : signed, unsigned

When the qualifier unsigned is used the number is always positive, and when signed is used number may be positive or negative. If the sign qualifier is not mentioned, then by default sign qualifier is assumed. The range of values for signed data types is less than that of unsigned data type. Because in signed type, the left most bit is used to represent sign, while in unsigned type this bit is also used to represent the value. The size and range of the different data types on a 16 bit machine is given below: Basic data type Data type with type qualifier Size (byte) Range char char or signed char Unsigned char

-128 to 127 0 to 255 int int or signed int unsigned int short int or signed short int unsigned short int long int or signed long int unsigned long int

-32768 to 32767 0 to 65535 -128 to 127 0 to 255 -2147483648 to 2147483647 0 to 4294967295 float float 4 -3.4E-38 to 3.4E+ double double Long double

1.7E-308 to 1.7E+ 3.4E-4932 to 1.1E+