lec 1 for ITC Introduction to computing and AI

lec 1 for ITC Introduction to computing and AI

• 1.
  Chapter # 1 INTRODUCTION CreatingYour First Program Compiling and Running Program Using Variables Displaying Values in Variable made by : Engr.Hira Zahid Working with Data Types Adding Comments
• 2.
  Learning Objectives •First courserelated to Computers – No previous knowledge is assumed ! •By the end of the course, students will: – Understand fundamental concepts of computer programming/imperative structured programming languages – Design algorithms to solve (simple) problems – Use the C programming language
• 3.
  How it works •How does a computer execute a program ? (example programs: a computer game, a word processor, etc) • the instructions that comprise the program are copied from the permanent secondary memory into the main memory • After the instructions are loaded, the CPU starts executing the program. • For each instruction, the instruction is retrieved from memory, decoded to figure out what it represents, and the appropriate action carried out. (the fetch- execute cycle) • Then the next instruction is fetched, decoded and executed.
• 4.
  Lecture outcome • Compilerand Interpreter • IDE • Header file and library files • Differentiate escape sequence & format specifier. • Constants & variables. • Types of data
• 5.
  • High levellanguages – Writing portable programs, using more abstract instructions – A high level instruction (statement) is translated into many machine instructions – Translation of high level language into machine instructions: done by special computer programs – compilers or interpreters
• 6.
  Compilers/Interpreters Compiler Source Code Machine Code Executable Program Input data Output data Interpreter Source Code Input data Output data Compiler: analyzes programand translates it into machine language Executable program: can be run independently from compiler as many times => fast execution Interpreter: analyzes and executes program statements at the same time Execution is slower Easier to debug program
• 7.
  The C ProgrammingLanguage • Developed by Dennis Ritchie at AT&T Bell Laboratories in the early 1970s
• 8.
  The first Cprogram #include <stdio.h> #include <conio.h> void main(void) { printf ("Programming is fun.n"); getch(); } uses standard library input and output functions (printf) the program begin of program end of program statements main: a special name that indicates where the program must begin execution. It is a special function. first statement: calls a routine named printf, with argument the string of characters “Programming is fun n” Getch() - it holds the screen
• 9.
  The format inC • Statements are terminated with semicolons”;” • Indentation is nice to be used for increased readability. • Free format: white spaces and indentation is ignored by compiler • C is case sensitive – pay attention to lower and upper case letters when typing ! – All C keywords and standard functions are lower case – Typing INT, Int, etc instead of int is a compiler error • Strings are placed in double quotes • New line is represented by n (Escape sequence)
• 10.
  Compiling and runningC programs Editor Compiler Linker Source code file.c Object code file.obj Executable code file.exe Libraries IDE (Integrated Development Environment)
• 11.
  Debugging program errors Editor Compiler Linker Sourcecode file.c Object code file.obj Executable code file.exe Libraries Syntactic Errors Semantic Errors
• 12.
  Syntax and Semantics •Syntax errors: violation of programming language rules (grammar) – "Me speak English good." – Use valid C symbols in wrong places – Detected by the compiler • Semantics errors: errors in meaning: – "This sentence is excellent Italian." – Programs are syntactically correct but don’t produce the expected output – User observes output of running program
• 13.
  Second program #include <stdio.h> #include<conio.h> void main (void) { printf ("Programming is fun.n"); printf ("And programming in C is even more fun.n"); getch(); }
• 14.
  Displaying multiple linesof text #include <stdio.h> #include <conio.h> void main (void) { printf("Testing...n..1n...2n....3n"); getch(); } Output: Testing... ..1 ...2 ....3 It is not necessary to make a separate call to printf for each line of output !
• 15.
  Constant & Variable
• 16.
  Variables • Programs canuse symbolic names for storing computation data and results • Variable: a symbolic name for a memory location – programmer doesn’t has to worry about specifying (or even knowing) the value of the location’s address • In C, variables have to be declared before they are used • Rules for constructing variable
• 19.
  keywords
• 20.
  Using and DisplayingVariables #include <stdio.h> #include <conio.h> void main (void) { int sum; sum = 50 + 25; printf ("The sum of 50 and 25 is %in", sum); getch(); } Variable sum declared of type int Variable sum assigned expression 50+25 Value of variable sum is printed in place of %i The printf routine call has now 2 arguments: first argument a string containing also a format specifier (%i), that holds place for an integer value to be inserted here
• 21.
  Displaying multiple values #include<stdio.h> #include <conio.h> void main (void) { float value1, value2, sum; value1 = 5.1; value2 = 2; sum = value1 + value2; printf ("The sum of %f and %f is %.2fn",value1, value2, sum); getch(); } The format string must contain as many placeholders as expressions to be printed
• 22.
  Using comments ina program • Comment statements are used in a program to document it and to enhance its readability. • Useful for human readers of the program – compiler ignores comments • Ways to insert comments in C: – When comments span several lines: start marked with /*, end marked with */ – Comments at the end of a line: start marked with //
• 23.
  Using comments ina program /* This program adds two integer values and displays the results */ #include <stdio.h> int main (void) { // Declare variables int value1, value2, sum; // Assign values and calculate their sum value1 = 50; value2 = 25; sum = value1 + value2; // Display the result printf ("The sum of %i and %i is %in", value1, value2, sum); return 0; }