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C-02
 

C-02

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    C-02 C-02 Presentation Transcript

    • Lecture 2Lecture 2 Version 1.0Version 1.0 Program StructureProgram Structure Memory ConceptMemory Concept
    • 2Rushdi Shams, Dept of CSE, KUET, Bangladesh Analyzing C Program Structure IAnalyzing C Program Structure I #include <stdio.h>#include <stdio.h> #include <conio.h>#include <conio.h> void main(){void main(){ clrscr();clrscr(); printf(“This is my first C program n”);printf(“This is my first C program n”); getch();getch(); }}
    • 3Rushdi Shams, Dept of CSE, KUET, Bangladesh Header fileHeader file #include <stdio.h>#include <stdio.h>  C Pre-processorC Pre-processor  Lines beginning with # are processed by the pre-Lines beginning with # are processed by the pre- processor before the program is compiledprocessor before the program is compiled  This line tells the pre-processor to include theThis line tells the pre-processor to include the contents of the standard input output header filecontents of the standard input output header file  To compileTo compile library functionlibrary function printf(), it is required.printf(), it is required.
    • 4Rushdi Shams, Dept of CSE, KUET, Bangladesh Header fileHeader file #include <conio.h>#include <conio.h>  Required for clrscr() and getch().Required for clrscr() and getch().
    • 5Rushdi Shams, Dept of CSE, KUET, Bangladesh main ( ) functionmain ( ) function void main( )void main( )  It is a part of every C programIt is a part of every C program  The parenthesis after main indicates that main is aThe parenthesis after main indicates that main is a program building block called aprogram building block called a functionfunction  C programs are composed of one or many functionsC programs are composed of one or many functions like it but main is a mustlike it but main is a must
    • 6Rushdi Shams, Dept of CSE, KUET, Bangladesh Library functionLibrary function clrscr();clrscr();  C library function.C library function.  Clears the contents present in the screen.Clears the contents present in the screen.
    • 7Rushdi Shams, Dept of CSE, KUET, Bangladesh Library functionLibrary function printf(“This is my first C program n”);printf(“This is my first C program n”);  C statement.C statement.  Statements are always terminated with aStatements are always terminated with a semi-colonsemi-colon  This statement has a library function called printf( )This statement has a library function called printf( )  It takes aIt takes a stringstring inside of it within twoinside of it within two quotation marksquotation marks  Whatever is in between them, will be printed on theWhatever is in between them, will be printed on the screenscreen  TheThe backslash ()backslash () character is calledcharacter is called Escape CharacterEscape Character  The escape sequence n meansThe escape sequence n means new linenew line
    • 8Rushdi Shams, Dept of CSE, KUET, Bangladesh Library functionLibrary function getch();getch();  Another C library functionAnother C library function  When the program compiles and provides an output,When the program compiles and provides an output, it waits for getting a character from the keyboardit waits for getting a character from the keyboard  When it gets, it returns from the output screen toWhen it gets, it returns from the output screen to source codesource code
    • 9Rushdi Shams, Dept of CSE, KUET, Bangladesh Analyzing C Program Structure IIAnalyzing C Program Structure II /* This program takes two integers/* This program takes two integers and provides the sum to the user */and provides the sum to the user */ #include <stdio.h>#include <stdio.h> // header file// header file #include <conio.h>#include <conio.h> //header file//header file // main function starts// main function starts void main(){void main(){ clrscr();clrscr(); // clearing the output screen// clearing the output screen int a,b,sum;int a,b,sum; // declaring three integers a, b and sum// declaring three integers a, b and sum printf(“Enter integer one: n”);printf(“Enter integer one: n”); // printing on output// printing on output scanf (“%d”,&a);scanf (“%d”,&a); //taking the input value into a//taking the input value into a printf(“Enter integer two: n”);printf(“Enter integer two: n”); // printing on output// printing on output scanf (“%d”,&b);scanf (“%d”,&b); // taking the input value into b// taking the input value into b sum=a+b;sum=a+b; // taking their summation into sum// taking their summation into sum printf(“Sum is: %d”, sum);printf(“Sum is: %d”, sum); // displaying the sum// displaying the sum getch();getch(); //waiting for a character to return//waiting for a character to return }}
    • 10Rushdi Shams, Dept of CSE, KUET, Bangladesh Multiline commentsMultiline comments  /* This program takes two integers/* This program takes two integers  and provides the sum to the user */and provides the sum to the user */  The characters /* … … … */ is calledThe characters /* … … … */ is called multi-linemulti-line commentingcommenting  When C finds this character, it omits what is insideWhen C finds this character, it omits what is inside that and goes to the next instructionthat and goes to the next instruction  Comments are required to make the program moreComments are required to make the program more readable and understandable if anyone analyzes thereadable and understandable if anyone analyzes the codecode
    • 11Rushdi Shams, Dept of CSE, KUET, Bangladesh Single line commentsSingle line comments // main function starts// main function starts  The characters // is calledThe characters // is called single line commentingsingle line commenting  Again, when C finds this character, it omits that line ofAgain, when C finds this character, it omits that line of codecode
    • 12Rushdi Shams, Dept of CSE, KUET, Bangladesh Variable declarationVariable declaration int a, b, sum;int a, b, sum;  It is aIt is a declarationdeclaration  The letters a, b and sum are names ofThe letters a, b and sum are names of variablesvariables  A variable is a location in memory where a value canA variable is a location in memory where a value can be stored for use by a programbe stored for use by a program  This declaration specifies that the variables a, b andThis declaration specifies that the variables a, b and sum are of typesum are of type intint which means that these variableswhich means that these variables will hold integer valueswill hold integer values  All variables must be declared with aAll variables must be declared with a namename and aand a datadata typetype
    • 13Rushdi Shams, Dept of CSE, KUET, Bangladesh Notes on variable namesNotes on variable names  A variable name in C is anyA variable name in C is any identifieridentifier. An identifier is a. An identifier is a series of characters consisting of letters, digits andseries of characters consisting of letters, digits and underscores (_) that does not begin with a digit.underscores (_) that does not begin with a digit.  It can be of any length. But C will understand the firstIt can be of any length. But C will understand the first 31 characters only.31 characters only.  C isC is case sensitivecase sensitive. Variable names like A1 and a1 are two. Variable names like A1 and a1 are two different variables.different variables.
    • 14Rushdi Shams, Dept of CSE, KUET, Bangladesh Library functionLibrary function scanf (“%d”,&a);scanf (“%d”,&a);  scanf () function to obtain a value from the userscanf () function to obtain a value from the user  The scanf () here has twoThe scanf () here has two argumentsarguments.. “%d”“%d” and &and &aa..  The % is Escape Character and %d is EscapeThe % is Escape Character and %d is Escape SequenceSequence  The second argument & (ampersand)- calledThe second argument & (ampersand)- called addressaddress operatoroperator in C followed by the variable name- tells‑in C followed by the variable name- tells‑ scanf() the location in memory in which the variable ascanf() the location in memory in which the variable a is stored.is stored.  The computer then stores the values forThe computer then stores the values for aa at thatat that locationlocation
    • 15Rushdi Shams, Dept of CSE, KUET, Bangladesh Use of binary operatorsUse of binary operators sum=a+b;sum=a+b;  It calculates the sum of variablesIt calculates the sum of variables aa andand bb and assignsand assigns the result to variable sum using the assignmentthe result to variable sum using the assignment operator =operator =  The + and = operators are calledThe + and = operators are called binary operatorsbinary operators asas they require twothey require two operandsoperands  The two operands of + are a and b and two operandsThe two operands of + are a and b and two operands of = are sum and a+bof = are sum and a+b
    • 16Rushdi Shams, Dept of CSE, KUET, Bangladesh Memory conceptMemory concept int a,b,sum;int a,b,sum;
    • 17Rushdi Shams, Dept of CSE, KUET, Bangladesh Memory conceptMemory concept scanf (“%d”,&a);scanf (“%d”,&a);
    • 18Rushdi Shams, Dept of CSE, KUET, Bangladesh Memory conceptMemory concept scanf (“%d”,&a);scanf (“%d”,&a); Say the input is 100Say the input is 100
    • 19Rushdi Shams, Dept of CSE, KUET, Bangladesh Memory conceptMemory concept scanf (“%d”,&b);scanf (“%d”,&b);
    • 20Rushdi Shams, Dept of CSE, KUET, Bangladesh Memory conceptMemory concept scanf (“%d”,&b);scanf (“%d”,&b); Say the input is 50Say the input is 50
    • 21Rushdi Shams, Dept of CSE, KUET, Bangladesh Memory conceptMemory concept sum=a+b;sum=a+b;