1. 1. C if elseIntroduction:-The if statement is used to conditionally execute a statement or ablock
of statements. Conditions can be true or false, execute onething when the condition is true,
something else when thecondition is false.
2. C if elseSyntax:- if (expression) statement(s); [else statement(s);]
3. C if elseExample :- if (a == b) printf ("%d is equal to %d", a, b); else printf ("%d is not equal to
%d", a, b);
4. C if elseIf-then statements :-Syntax:- if (expression) statement(s);
5. C if elseIf-then statements :-Example:- if (a == b) printf ("%d is equal to %d", a, b); else printf
("%d is not equal to %d", a, b);Note : There is no indentation rule in writing C programming, we
can write the abovecode in following ways :
6. C if elseIf-then statements :-Example:- if (a == b) printf ("if a is equal to b"); printf ("%d is
equal to %d", a, b); if (a == b) { printf ("if a is equal to b"); printf ("%d is equal to %d", a, b); }Note
: The second way of writing code is a good practice.
7. C if elseA complete example on conditional if-else statement:-Example :- #include<stdio.h>
main() { int num; printf("Input a number : "); scanf("%d",&num); if(num>0) { printf("This is a
positive integern"); } else // else portion of if statement { printf(" This is not a positive
integer..Try againn") ; } }
8. C if elseA complete example on conditional if-else statement:-Example :- #include<stdio.h>
main() { int num; printf("Input a number : "); scanf("%d",&num); if(num>0) { printf("This is a
positive integern"); } else // else portion of if statement { printf(" This is not a positive
integer..Try againn") ; } }
9. C if elseSequential if-then statements :-Example :- if (a == b) printf ("a = b"); if (a == c) printf
("a = c"); if (b == c) printf ("b = c")
10. C if elseMultiway if-else-Statement :-syntax :- if (expression_1) statement_1 else if
(expression_2) statement_2 . . . else if (expression_n) statement_n else other_statement
11. C if elseMultiway if-else-Statement :- #include<stdio.h> main()Example :- { int num;
printf("Input score :"); scanf("%d",&num); if (num>=90) { printf("Grade : Excellent"); } else
if(num>=80 && num<90) { printf("Grade : Very Good"); } else if(num>=60 && num<80)
{ printf("Grade : Good"); } else if(num>=50 && num<60) { printf("Grade : Average"); } else
if(num>=40 && num<50) { printf("Grade : Poor"); } else { printf("Grade : Not Promoted"); } }
12. C if elseNested if-then-else statements :-Example :- #include<stdio.h> main() { int num1=5,
num2=3, num3=-12, min; if(num1<num2) { if(num1<num3) min = num1; else min = num3; } else
{ if(num2<num3) min = num2; else min = num3; } printf("Among %d, %d, %d minimum number
is %d",num1 ,num2,num3,min); }