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Decision Making in C



DECISION MAKING IN C

When we need to execute a problem in  accordance to the condition, in a  program, or to check any valid argument in a program, we need a favorable method to execute the program, this is where Decision Making steps in programming.

Think of a ROUNDABOUT where, on left lane is your home, on right is your friend's home ,forward is market, and back is hospital, you need to decide on which lane/road you need to move, hence you execute your passage through that lane to reach  your destination, decision making works in same way where you get to decide what to do according to desired condition.

For example in real world: if you need to go to hospital from roundabout  you need to take U-Turn and go thus you make a decision, since you decided to go to hospital, your condition is taking a U-Turn.

For example in programming: if you need to print your age when '1' is pressed and or name when '2' is pressed, the condition is to press either 1 or 2 and outcome is printing your age or name  accordingly.

Decision making is done through decision making statements; there are mainly three decision making statements in C.

* IF STATEMENTS
* IF ELSE STATEMENTS
* IF ELSE-IF ELSE STATEMENTS





THE IF STATEMENTS

The If statements are used to check whether a condition or a set of conditions is true or not. If the condition is true then only the desired actions, commands are executed, otherwise that set of code is skipped.

SYNTAX:

if(condition)
{
     Statements,commands to execute
}

EXAMPLE:
  • To find if a number is even.

We know that a number is even if it is divisible by 2 and gives 0 as remainder when divided by 2

CODE:

if(number%2==0)
{
    printf("THE NUMBER IS EVEN");
}


  • To find if number is divisible by 5 and 7
CODE:

if(number%5==0 && number%7==0)
{
   printf("DIVISIBLE BY BOTH NUMBER");
}

   THE IF-ELSE STATEMENTS

When the requirement is to check one condition or set of conditions and to execute statements according to that & to execute some other statements when if condition does not satisfy then If-Else statements are used.
Conditions are only carried out only in If statements. Else do not hold any condition,but just statements to execute within parenthesis.

SYNTAX:

if(condition)
{
     Statements,commands to execute
}
else
{
     Statements,commands to execute
}

EXAMPLE:
  • To find and print if a number is divisible by 7 or not.

CODE:

if(number%7==0)
{
    printf("THE NUMBER IS DIVISIBLE BY 7");
}
else
{
   printf("NOT DIVISIBLE BY 7");
}

  • To find and print if a number is greater than 10 or not.
CODE:

if(number>10)
{
   printf("GREATER THAN 10");
}
else
{
   printf("LESS THAN 10");
}


   THE IF-ELSE-IF-ELSE STATEMENTS

When the requirement is to check one condition or set of conditions and to execute statements according to that & to check other condition if first one is false and execute statements this method is referred to as If-Else-if-else statements are used.

There can be any number on else-if cases and only one else condition.

SYNTAX:

if(condition)
{
     .....statements
}
else if//1st
{
     ...Statements
}
:
:
:
else if //nth
{ 
    ....statements
}
else
{ 
..statements
}

EXAMPLE:
  • To find if number is greater than 10 or less than 10 or 10 itself.

CODE:

if(number<10)
{
    printf("THE NUMBER IS LESS THAN 10");
}
else if(number>10)
{
   printf("THE NUMBER IS GREATER THAN 10);
}
else
{
printf("NUMBER IS 10");
}

****

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