if-else Statements
Till
now,we just threw light on uses of 'if'. Now its about time we should
head for the counter part of 'if' i.e. 'else'. Its very easy to take
down this topic in one shot. So we'll discuss just a single program regarding this topic.
What basically 'else' refers to is the left over of 'if'. In simple
language, consider we write our 'if' condition as if(i<8), then this
'if' will include all the values of i which are smaller than 8(not
including 8). Now the left over of this 'if' are the values of i
including 8,9,10 ......and all above values.These values are covered in
else.The syntax of writing 'if' with 'else' is as follows:
if(condition)
statement 1;
else
statement 2;
Remember,
unlike 'if' statements we do not need to write any condition in 'else'
statements which are covered by a pair of brackets. All
the conditions which are not a part of 'if' are automatically covered
in 'else'. In the last example we read in 'if' topic which had a logical
NOT operator (!), the second 'if' can be replaced by else.Why is it so
you ask? It is because all the conditions not satisfied by 'if' were
FALSE. And NOT operator changes all these FALSE conditions to TRUE. So
indirectly it is including all the conditions left by 'if'. Lets
consider an example.
#include<iostream>
#include<cstdlib>
using namespace std;
int main()
{
int a;
cout<<"\nEnter value of a : ";
cin>>a;
if(a==2609)
cout<<"\n Holla!!!! Thats my birthday";
else
cout<<"\nNop! Thats not my BD.";
system("PAUSE");
return 0;
}
For
creating a link between this program with the one we studied
earlier(one having NOT operator), I'll only say,we could have written
that program in the following way:
#include <cstdlib>
#include <iostream> //Header Files
#include <iostream> //Header Files
using namespace std;
int main() //main function
{
system("CLS"); //clears any printed, if any
int condition;
cout<<"\nEnter value of condition : ";
cin>>condition;
if(condition) // 1st if
cout<<"\nYour condition evaluates to TRUE.";
else // Replacement of 2nd if
cout<<"\nYour condition evaluates to FALSE.";
system("PAUSE"); // Freeze the screen to show the output
return 0;
}
{
system("CLS"); //clears any printed, if any
int condition;
cout<<"\nEnter value of condition : ";
cin>>condition;
if(condition) // 1st if
cout<<"\nYour condition evaluates to TRUE.";
else // Replacement of 2nd if
cout<<"\nYour condition evaluates to FALSE.";
system("PAUSE"); // Freeze the screen to show the output
return 0;
}
The concept is easy and self explanatory.The next topic we'll be covering is "multiple statement under if and else".
Written By T-Rex
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