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Decision control instructs
Relation operators. If statement. Nested if statement. If else
statement. Nested if else statement. Logical operators. Else if
clause. Conditional operators.
Relation operators: a relational operator is a programming
language construct or operator that tests or
defines some kind of relation between two entities. These
include numerical equality (e.g., 5 = 5) and
inequalities (e.g., 4 3).
x==y x is equal to y. x != y x is not equal to y. x y x is
grater than y. x=y x is grater than or equal to.
Conditional statements: In computer science, conditional
statements, are features of a programming
language which perform different computations or actions
depending on whether a programmer-specified
boolean condition evaluates to true or false.
If statement :
if (condition)
execute this statement;
OR
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if (condition)
{
statement 1;
statement 2;
}
If else statement :
if (condition)
statement 1;
else
statement 2;
OR
if (condition)
{
statement 1;
}
else
{
statement 2;
}
Nested if else:
if (condition)
{
if (condition){
statement 1;
}
else
{
statement 2;
}
}
else
{
statement 2;
}
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Logical operator:
C# provides a large set of operators, which are symbols that
specify which operations to
perform in an expression. Operations on integral types such as
,
&& AND operator. || OR operator. ! NOT operator.
Loop Control Instruction :
While loop For loop Break statement Continue statement Do-while
loop
While loop :
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Example problem : Simple interest program
static void Main (String[] args)
{
int p,n,count;
float r,si;
count=1
while(count
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For loop: this looping technique is probably the most popular
looping instruction. Because for allows us
to specify three things about a loop in a single line :
Initial values. Testing condition. Incrementation/
decrementation.
Example for the same si problem :for(i=1;i
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Continue statement:
Continue statement is used to get out of the loop with out
executing the remaining statements. Continue statement is usually
associated with if.
The do-while loop:
In While , the condition is tested before the execution . But in
do-while , the statements are executedfirst and then condition is
tested.
Do{
statement 1;
statement 2:
} while (condition);
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Case Control Statement:
Decision Using switch: the control statement that allows us to
make a decision from the number of choices is
called a switch.
Example:
Static void main (string[]args)
{
int i= ? ;
switch(i)
{
case 1:
Console.WriteLine(I am in case 1);
break;
case 2:
Console.WriteLine(I am in case 2);
break;
case 3:
Console.WriteLine(I am in case 3);
break;
default :
Console.WriteLine(I am default);
break;
} }
Tips:
Case statements can be put in any order. Every statement in the
switch must belong to some case . The break program when used in
the switch takes control out side the switch. But the use of
continue will not take the control to the beginning of switch.
Goto:
In a difficult programming situation , it seems to so easy to
use a goto to take the control where youwant. However , almost
always there is a better way of writing the same program using
if,for,while and
switch. These construct are far more logical and easy to
understand.
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