If statement

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1. void main() 2. { 3. int a=5,b=6,c; 4. c = a + b ; 5. if (c==11) 6. printf("Execute me 1"); 7. printf("Execute me 2"); 8. } 9. Output :

10. Execute me 1

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Else-if Ladder in C : Decision Making

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If Else Ladder / Else-If Clause
Syntax of Else-If Ladder :

view plainprint? 1. #include 2. if(expression1) 3. statement1; 4. else if(expression2) 5. statement2; 6. else if(expression3) 7. statement3; 8. else 9. statement4;
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Explanation : • Conditions are evaluated from Top to Bottom • As soon as TRUE expression is found the statement associated with it is executed and rest of the ladder isBypassed
Flowchart :
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Sample Example : To find the Grade of the Student)

view plainprint? 1. if (marks >= 67 ) 2. printf("Distinction"); 3. else if (marks >=60) 4. printf("First Class"); 5. else if (marks >=55) 6. printf("Higher Second Class"); 7. else if (marks >=50) 8. printf("Second Class"); 9. else if (marks >=40) 10. printf("Pass Class"); 11. else 12. printf("Fail");
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If – else statement

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1. void main() 2. { 3. int marks=50; 4. if(marks>=40) 5. { 6. printf("Student is Pass"); 7. } 8. else 9. { 10. printf("Student is Fail"); 11. } 12. }

Sample Output :

view plainprint? 1. Student is Pass

switch case in C Programming Language

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Switch case in C Programming
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Must Read :

Switch Case
Rules of using switch
Illegal ways of Using switch
Valid Ways of using switch case
Switch case : Tricky Questions ?
Why Need arises ? • One of the classic problem encountered in nested if-else / else-if ladder is called problem of Confusion. • It occurs when no matching else is available for if . • As the number of alternatives increases the Complexity of program increases drastically. • To overcome this , C Provide a multiway decision statement called 'switch'

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Syntax :

switch ( expression ) { case value1 : body1 break;

case value2 : body2 break;

case value3 : body3 break; - - - - - - - - - - - - - - - - - - default : default-body break;

} next-statement;

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How it works ? • Switch case checks the value of expression/variable against the list of case values and when the match is found , the block of statement associated with that case is executed • Expression should be Integer expression / Character • Break statement takes control out of the case.

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Example and Steps of Execution : 1. #include 2. #include 3. void main() 4. { 5. int roll = 3 ; 6. switch ( roll ) 7. { 8. case 1 : 9. printf ( " I am Pankaj "); 10. break; 11. case 2 : 12. printf ( " I am Nikhil "); 13. break; 14. case 3 : 15. printf ( " I am John "); 16. break; 17. default : 18. printf ( "No student found"); 19. break; 20. } 21. getch() 22. }
As explained earlier - 1. 3 is assigned to integer variable 'roll' 2. As control goes to line number 6 above switch case will replace the 'roll' by 3 So temporarily line 6 changes to switch ( 3 ) 3. This checks matching case having expression '3' 4. As it founds the matching case it Executes the body and output as ' I am John ' 5. After executing the body , break takes control out of the switch case i.e line number 21 6. Suppose no matching case found then default case and its body is executed /////////////////////////////////////////////////////////////////////////////
Rules of using Switch case in C Programming

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Rules of using Switch case
Syntax :

view plainprint? 1. switch ( expression ) 2. { 3. case label1 : 4. body1 5. break; 6. 7. case label2 : 8. body2 9. break; 10. 11. caselabel3 : 12. body3 13. break; 14. default : 15. default-body 16. break; 17. } 18. next-statement;
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Rules : • Case Label must be unique • Case Labels must ends with Colon • Case labels must have constants / constant expression • Case label must be of integral Type ( Integer,Character) • Case Labels Should not have float • Case label should not be 'floating point number ' eg. (case 4.5 :) is not allowed • Switch case should have at most one default label • Default label is Optional • Default should be placed anywhere in the switch • Break Statement takes control out of the switch • Two or more cases may share one break statement • Nesting ( switch within switch ) is allowed /////////////////////////////////////////////////////////////////////////////
Illegal Use of Switch Case

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Illegal Use of Switch Case !!!
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Case 1 : Floating Case Not Allowed !!! 1. i = 1.5 2. switch ( i ) 3. { 4. case 1.3 : 5. printf ("Case 1.3"); 6. break; 7. case 1.4 : 8. printf ("Case 1.4"); 9. break; 10. case 1.5 : 11. printf ("Case 1.5"); 12. break; 13. default : 14. printf ("Default Case "); 15. } 16. getch(); 17. }

Case 2 : Case Labels Should be Unique 1. i = 1; 2. switch ( i ) 3. { 4. case 1 : 5. printf ("Case 1"); 6. break; 7. case 1 : 8. printf ("Case 2"); 9. break; 10. case 3 : 11. printf ("Case 3"); 12. break; 13. default : 14. printf ("Default Case "); 15. } 16. getch(); 17. }
Case 3 : Case Labels Should not Contain any Variable 1. i = 1; 2. switch ( i ) 3. { 4. case 1 : 5. printf ("Case 1"); 6. break; 7. case i + i : 8. printf ("Case 2"); 9. break; 10. case 3 : 11. printf ("Case 3"); 12. break; 13. default : 14. printf ("Default Case "); 15. } 16. getch(); 17. }

Case 4 : All Cases must wrapped in any of the case
( Generally Compiler won't show Error Message but It will neglect statement which does not belongs to any case) 1. i = 1; 2. switch ( i ) 3. { 4. printf ( "HI,Hello") // It does not belongs to any case 5. case 1 : 6. printf ("Case 1"); 7. break; 8. case 2 : 9. printf ("Case 2"); 10. break; 11. case 3 : 12. printf ("Case 3"); 13. break; 14. default : 15. printf ("Default Case "); 16. } 17. getch(); 18. }
Output :
Case 1

Case 5 : Comparison Not allowed 1. i = 1; 2. switch ( i ) 3. { 4. case i11 : 11. printf ("Case 3"); 12. break; 13. default : 14. printf ("Default Case "); 15. } 16. getch(); 17. }

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Syntax : switch ( expression ) { case value1 : body1 break;

case value2 : body2 break;

case value3 : body3 break; - - - - - - - - - - - - - - - - - - default : default-body break;

} next-statement; /////////////////////////////////////////////////////////////////////////////
Acceptable Forms of Switch Case

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Acceptable Forms of Switch Case !!!
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Case 1 : Integer Allowed 1. i = 1; 2. switch ( i ) 3. { 4. case 1 : 5. printf ("Case 1"); 6. break; 7. case 2 : 8. printf ("Case 2"); 9. break; 10. case 3 : 11. printf ("Case 3"); 12. break; 13. default : 14. printf ("Default Case "); 15. } 16. getch(); 17. }
Case 2 : Character Allowed 1. ch = 'a'; 2. switch ( ch ) 3. { 4. case 'a' : 5. printf ("Case Apple"); 6. break; 7. case 'b' : 8. printf ("Case Ball"); 9. break; 10. case 'c' : 11. printf ("Case Cat"); 12. break; 13. default : 14. printf ("Default Case "); 15. } 16. getch(); 17. }
Case 3 : May Share one break Statement 1. char ch = 'a' 2. switch ( i ) 3. { 4. case 'A' : 5. case 'a' : 6. printf ("Case Apple"); 7. break; 8. case 'B': 9. case 'b': 10. printf ("Case Ball"); 11. break; 12. case 'c' : 13. printf ("Case Cat"); 14. break; 15. default : 16. printf ("Default Case "); 17. } 18. getch(); 19. }

Case 4 : Order Does not matters ( case 4 comes before case 1)

1. i = 1; 2. switch ( i ) 3. { 4. default : 5. printf ("Default Case "); 6. break; 7. case 4 : 8. printf ("Case 4"); 9. break; 10. case 2 : 11. printf ("Case 2"); 12. break; 13. case 1 : 14. printf ("Case 1"); 15. break; 16. } 17. getch(); 18. }
Case 5 : Constant Expressions Allowed

1. i = 1; 2. switch ( i ) 3. { 4. case 1 : 5. printf ("Case 1"); 6. break; 7. case 7-5 : 8. printf ("Case 2"); 9. break; 10. case 6/2 : 11. printf ("Case 3"); 12. break; 13. default : 14. printf ("Default Case "); 15. break; 16. } 17. getch(); 18. }
Case 6 : Nesting Allowed 1. i = 1,j=8; 2. switch ( i ) 3. { 4. case 1 : 5. switch ( j ) 6. { 7. case 8 : 8. printf ("Nested Case 8"); 9. break; 10. case 9 : 11. printf ("Nested Case 9"); 12. break; 13. } 14. 15. case 2 : 16. printf ("Case 2"); 17. break; 18. case 3 : 19. printf ("Case 3"); 20. break; 21. default : 22. printf ("Default Case "); 23. } 24. getch(); 25. }
Case 7 : Default May Be absent 1. i = 1; 2. switch ( i ) 3. { 4. case 1 : 5. printf ("Case 1"); 6. break; 7. case 2 : 8. printf ("Case 2"); 9. break; 10. case 3 : 11. printf ("Case 3"); 12. break; 13. } 14. getch(); 15. } ////////////////////////////////////////////////////////////////////////////////////////////////////////

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Conditional Operators [ ?: ] in C

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Conditional Operators [ ?: ] in C
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1. They are also called as Ternary Operator . 2. They also called as ?: operator 3. Ternary Operators takes on 3 Arguments
Syntax :

expression 1 ? expression 2 : expression 3
Meaning of Syntax : 1. expression1 is nothing but Boolean Condition i.e it results into either TRUE or FALSE 2. If result of expression1 is TRUE then expression2 is Executed 3. Expression1 is said to be TRUE if its result is NON-ZERO 4. If result of expression1 is FALSE then expression3 is Executed 5. Expression1 is said to be FALSE if its result is ZERO
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Goto Statement in C Programming Language

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Goto Statement in C Programming Language
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• Goto is Unconditional Jump . • Simply Jumps from One point to another in C Program • Forward jump & Backward Jump are two Types of goto Statement. • Generally Unconditional Jump is Used in Assembly Languages
Goto Syntax : 1. Goto Breaks the Normal flow of Program 2. Goto Requires the Label in Order to identify the place where the branch is to be made 3. Syntax : goto label ; // Goto followed by Label 4. label : -- It Should be any Valid Variable Name -- Label Should be Terminated by Colon ( : )

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Goto Downward Jump / Forward jump :

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Goto upward jump / Backward Jump :

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Drawbacks of Goto : 1. Infinite Loop ( Example of Infinite Loop )
| main () |
| { |
| int n1,n2; |
| read : |
| scanf ( "%d",&n1); |
| n2 = n1 * n1 ; |
| printf ( "Square : %d",n2); |
| goto read ; |
| } |

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Different forms of break statement in C Programming

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Different forms of break
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