MATLAB - Conditional Statements - GeeksforGeeks

26 Nov, 2020
Conditional statements are something that is very basic and important for every programmer. There will be some situations where a program or a particular block has to be executed only when a specific condition is True. These conditional statements will be very handy and fruitful in such situations. These conditional statements work as same as in other languages. However, syntax varies from language to language. The following are the conditional statements that we can use in MATLAB.
if-end
if-else-end
nested-if-end
if-elseif-elseif-else-end
switch case
nested switch case
An if-end statement is the simplest decision-making statement. It decides whether a particular block of code has to be executed or not, based on the given boolean condition. Only when the given condition is true, it executes the statements inside the block otherwise not.
Syntax:
if (condition)
  % statement(s) will execute
  % if the boolean expression is true  
  <statements>
end
Example:
MATLAB
% MATLAB program to illustrate% if-end statement  number = 28;  if number>10    fprintf('The number is greater than 10.');end
 Output:
The number is greater than 10.

In conditional if Statement the additional block of code is merged as else statement which is performed when if the condition is false else condition won’t be executed when if the condition is True. 
Syntax:
if (condition)
  % statement(s) will execute
  % if the boolean expression is true  
  <statement(s)>
else
  <statement(s)>
  % statement(s) will execute 
  % if the boolean expression is false  
end
Example 1:
MATLAB
% MATLAB program to illustrate% if-else-end statement  number = 28;  if number<10    fprintf('The number is greater than 10');else    fprintf('The number is not less than 10');end
 Output:
The number is not less than 10

Example 2: You can also chain if-else-end statements with more than one condition.
MATLAB
% MATLAB program to illustrate% if-else chaining  number = 28;  if number<10    fprintf('The number is less than 10\n');else    if number<20        fprintf('The number is less than 20\n');    else        fprintf('The number is less than 30\n');    endend
Output:
The number is less than 30

There comes some situations where multiple conditions have to be satisfied to execute a block of code then we use nested if-end statements. This is nothing but another if condition(s) inside an if condition.
Syntax:
if (condition)
  % Executes when the boolean expression 1 is true  
  if (condition)
     % Executes when the boolean expression 2 is true    
  end
end
Example:
MATLAB
% MATLAB program to illustrate% Nested if-end statements  number = 2;  if number<10    fprintf('The number is less than 10\n');          % Executes when then above if    % condition is true    if number<5        fprintf('Also The number is less than 5');    end      end
Output:
The number is less than 10
Also The number is less than 5

An if statement can be followed by one (or more) optional elseif and an else statement, which is very useful to test various conditions.
Syntax:
if (condition)
  % Executes when the expression 1 is true  
  <statement(s)>
elseif (condition)
  % Executes when the boolean expression 2 is true
  <statement(s)>
elseif (condition)
  % Executes when the boolean expression 3 is true  
  <statement(s)>
else  
  %  executes when the none of the above condition is true  
  <statement(s)>
end
Example:
MATLAB
% MATLAB program to illustrate% if-elseif-else-end statement  number = 28;  if number<10    fprintf('The number is less than 10\n');elseif number<20    fprintf('The number is less than 20\n');elseif number<30    fprintf('The number is less than 30\n');else    fprintf('The number is less than 40\n');end
 Output:
The number is less than 30

A switch block is familiar to if-elif-else-end statements. It works as same as in other languages except for syntax. But there are few key differences between them. A switch block conditionally executes one set of statements from several choices. Each choice is covered by a case statement. A switch expression can be any of the following.
Numbers
Characters
Strings
Objects
Here comparison of string expressions and case expressions is case-sensitive. Every character of a switch string expression must be matched with the case string expression.
Syntax:
switch (condition)
  case condition
     <statements>
  case (condition)
     <statements>
     ...
     ...
  otherwise
     <statements>
end
Example 1:
MATLAB
grade = 'A';   switch(grade)   case 'A'       fprintf('Excellent!\n' );   case 'B'       fprintf('Well done\n' );   case 'C'       fprintf('Good\n' );   case 'D'      fprintf('You passed\n' );   case 'F'       fprintf('Better try again\n' );   otherwise      fprintf('Invalid grade\n' );   end
 Output:
Excellent!

Example 2: 
MATLAB
% MATLAB program to illustrate% String evaluation while using% switch case  % First letter of the name was% given small letter intentionallyname = 'geeksforGeeks'    switch(name)    case 'GeeksforGeeks'        fprintf('Hello from %s',name);    otherwise        fprintf('Not Matched!');end
Output:
Not Matched!


Example 3:
MATLAB
% MATLAB program to illustrate% switch case  days = 28;  switch(days)   case 28       fprintf('Normal Year!\n' );   otherwise      fprintf('Leap Year\n' );end
 Output:
Normal Year!

This is similar to nested if statements. We can use switch as a part of the statement inside a switch. Even if the case constants of the inner and outer switch contain common values, no conflicts will arise. 
Syntax:
switch (condition) 
  case (condition)  
     <statements>
     switch (condition)  
        case (condition)
        <statements>
              .....
     end    
  case (condition)
     <statements>
end
Example: This example explains how the nested switch case and string comparison works in MATLAB.
MATLAB
% MATLAB program to illustrate% nested switch case  days = 29;month = 'February'    switch(days)   case 29       fprintf('This Year is ' );   switch month       case 'february'           fprintf('Leap Year!\n' );       otherwise           fprintf('Not Leap Year!\n' );   end     end
Output:
This Year is Not Leap Year!

Note:
Unlike other programming languages, we don’t need to use break statement in switch case.Unlike other programming languages, we don’t use any kind of parentheses (i.e., (),{},: ) while writing conditions in conditional statements(i.e., if, nested if, etc). We do use end statement to end a conditional statement.Use semi-colons(;) wherever necessary to avoid unwanted outputs.
Unlike other programming languages, we don’t need to use break statement in switch case.
Unlike other programming languages, we don’t use any kind of parentheses (i.e., (),{},: ) while writing conditions in conditional statements(i.e., if, nested if, etc). We do use end statement to end a conditional statement.
Use semi-colons(;) wherever necessary to avoid unwanted outputs.
MATLAB
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