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Selection Feature of C:
• Decision making statements:• It allow us to take decisions
as to which code is to be executed next. Since these statements ‘control’ the flow of execution , they are also known as control statements.In C these statements are:
a)If statementb)Switch statement
If statement It can be used in following ways:
Simple if statement
If-else statement
If-else if statement
Nested if statement
SIMPLE IF SIMPLE IF STATEMENTSTATEMENT
SYNTAX:If (this condition is true){
statement;}
Note:If there is only one statement in if block then there is no need of curly braces.
GENERAL CONDITIONS USED IN FOR LOOP
x==y x!=y x<y x>y x<=y x>=y
x is equal to y x is not equal to y x is less than y x is greater than y x is less than or
equal to y x is greater than or
equal to y
This expression Is true if
EXAMPLE:#include <stdio.h>void main(){int i;i=5;if(i==5){printf(“Inside if \n”);printf(“This proves i=5”);}}
Output:Inside ifThis proves i=5
IF-ELSE STATEMENTIF-ELSE STATEMENTSyntax:if(condition){
no. of statements}else{
no. of statements}
start
Condi-tion
Statem-ent
Execute statement
NO
YES
EXAMPLE:#include<stdio.h>void main()
{int x;x=2;if(x<10)
printf(“x<10 is true \n”);else
printf(“x<10 is false”);printf(“this is outside if and else”);
}
OUTPUT:x<10 is trueThis is outside if and else
IF-ELSE IF STATEMENT IF-ELSE IF STATEMENT (LADDER IF)(LADDER IF)
syntax:
if(condition){
no. of statements;}else if(condition){
no. of statements;}else{
no. of statements;}
EXAMPLE:
#include<stdio.h>void main(){int a;a=1;if(a==4)printf(“I’m in 4th yr”);else if(a==3)
printf(“I’m in 3rd yr”);else if(a==2)
printf(“I’m in 2nd yr”);else
printf(“I’m in 1st yr”);
}
OUTPUT:I’m in 1st yr
NESTED IF STATEMENTNESTED IF STATEMENTA conditional statement inside another conditional
statement is called nested conditional statement. They are used to implement multi way decision.
syntax:if(condition){
if(condition){
no. of statements;}
}else{
if(condition)no. of statements;
}
EXAMPLE:
#include<stdio.h>void main(){int a;char c;a=20;c=‘f’;if(c==‘f’){
printf(“Costumer is female \n”);if(a< 16)printf(“Her age is less than 16, so she’ll get a concession of 5%”);
}
else{
printf(“Costumer is male\n”);if(a>50)printf(“His age is more than 50, so he’ll get a concession of 5%”);
}}
OUTPUT:Costumer is female
NOTE:If in above example,
a=10 ;
Then,
If in above example,
a=60;
c=‘m’;
OUTPUT:Costumer is femaleHer age is less than 16, so she’ll get a concession of 5%
OUTPUT:Costumer is maleHis age is more than 50, so he’ll get a concession of 5%
IF……….IF..ELSE………..ELSE:
Syntax: if(condition){
if(condition)execute the body
elseexecute the body
}
Else{
execute the body}
EXAMPLE:
#include<stdio.h>void main(){int a,b;a=10;b=20;if(a!=b){
printf(“a is not equal to b”);if(a>b)
printf(“a is greater than b”);
elseprintf(“a is less than b”);
}elseprintf(“a is equal to b”);}
OUTPUT:a is not equal to ba is less than b
SWITCH STATEMENTSWITCH STATEMENTIt can be used to select one option among multiple
options. switch can replace if-else if statement(ladder if)
syntax:
switch(variable){
case value1:no. of statements;break;
case value2:no. of statements;break;
case valueN:no. of statements;break;
default:no. of statements;
}
There is no need to write break statement at last option.
If you do not write break statement with any option the next option will be executed.
default can be put any where in the switch block.Example 1:
#include<stdio.h>void main(){int t;t=2;switch(t){case 1: printf(“t is equal to 1\n”);
break;case 2: printf(“t is equal to 2\n”);
break;case 3: printf(“t is equal to 3\n”);
break;default: printf(“t is not found\n”);}}
OUTPUT:t is equal to 2
EXAMPLE2:
#include<stdio.h>void main(){int t;t=2;switch(t){case 1: printf(“t is equal to 1\n”);
break;case 2: printf(“t is equal to 2\n”);case 3: printf(“t is equal to 3\n”);default: printf(“t is not found\n”);}}
OUTPUT:t is equal to 2t is equal to 3t is not found
EXAMPLE3:
#include<stdio.h>void main(){int t;t=5;switch(t){case 1: printf(“t is equal to 1”);
break;default: printf(“t is not found”);case 2: printf(“t is equal to 2”);
break;case 3: printf(“t is equal to 3”);}}
OUTPUT:t is not foundt is equal to 2
?: OPERATOR This is a operator which is capable ofcontrolling the flow of control. syntax:Conditional expression ? Expression
1: expression 2
Conditional expression
Expression 1Expression 2
: ?
Example:1.…..int a=5;a>5?printf(“a=5”):printf(“a!=5”);….Output:a=52.…..int a=6;a>5?printf(“a=5”):printf(“a!=5”);….Output:a!=5
