MATLAB- Structured Programming - PowerPoint Presentation, Engineering, Semester IT & Software Notes | EduRev

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1
Structured Programming Structured Programming
KMU 255 KMU 255- - Computer Programming Computer Programming
Hacettepe University Hacettepe University
Department of Chemical Engineering Department of Chemical Engineering
2012 2012- -2013 Fall Semester 2013 Fall Semester
Dr. Eda Dr. Eda Ç Çelik elik- -AKDUR AKDUR
Structured Programming: 1 Structured Programming: 1- -Decisions Decisions
If condition
statements
end
Page 2


1
Structured Programming Structured Programming
KMU 255 KMU 255- - Computer Programming Computer Programming
Hacettepe University Hacettepe University
Department of Chemical Engineering Department of Chemical Engineering
2012 2012- -2013 Fall Semester 2013 Fall Semester
Dr. Eda Dr. Eda Ç Çelik elik- -AKDUR AKDUR
Structured Programming: 1 Structured Programming: 1- -Decisions Decisions
If condition
statements
end
2
Structured Programming (Flow Control) Structured Programming (Flow Control)
Conditionals: Conditionals: If If/ /elseif elseif/else /else
s switch witch/c /case ase, try/catch , try/catch
Loops: Loops: while while, , error error, ,
for, break, for, break, 
return, continue return, continue
Slide reproduced from Selis Önel’s KMU206 lecture notes with permission
The   if…elseif structure
Note that indentation helps to make programs easier to read, esp. if you 
have long programs.
Page 3


1
Structured Programming Structured Programming
KMU 255 KMU 255- - Computer Programming Computer Programming
Hacettepe University Hacettepe University
Department of Chemical Engineering Department of Chemical Engineering
2012 2012- -2013 Fall Semester 2013 Fall Semester
Dr. Eda Dr. Eda Ç Çelik elik- -AKDUR AKDUR
Structured Programming: 1 Structured Programming: 1- -Decisions Decisions
If condition
statements
end
2
Structured Programming (Flow Control) Structured Programming (Flow Control)
Conditionals: Conditionals: If If/ /elseif elseif/else /else
s switch witch/c /case ase, try/catch , try/catch
Loops: Loops: while while, , error error, ,
for, break, for, break, 
return, continue return, continue
Slide reproduced from Selis Önel’s KMU206 lecture notes with permission
The   if…elseif structure
Note that indentation helps to make programs easier to read, esp. if you 
have long programs.
3
The   if…elseif structure

 If control_expr_1 is true (nonzero), then 
the program executes the statements in 
Block 1 and skips to the first executable 
statement following the  end.

 Otherwise, the program checks for the 
status of control_expr_2. If control_expr_2
is true (nonzero), then the program executes 
the statements in Block 2 and skips to the 
first executable statement following the end. 

 If all control expressions are zero,
then the program executes the statements in 
the block associated with the else clause.

 There can be any number of elseif 
clauses (0 or more) in an if construct, but 
there can be at most one else clause.
Example 3.2—The Quadratic Equation
Write a program to solve for the roots of a quadratic equation. The inputs 
required by this program are the coefficients a, b, and c of the quadratic eqn.
If b
2
-4ac > 0, two distinct real roots
If b
2
-4ac = 0, single repeated root
If b
2
- 4ac < 0, two complex roots
Page 4


1
Structured Programming Structured Programming
KMU 255 KMU 255- - Computer Programming Computer Programming
Hacettepe University Hacettepe University
Department of Chemical Engineering Department of Chemical Engineering
2012 2012- -2013 Fall Semester 2013 Fall Semester
Dr. Eda Dr. Eda Ç Çelik elik- -AKDUR AKDUR
Structured Programming: 1 Structured Programming: 1- -Decisions Decisions
If condition
statements
end
2
Structured Programming (Flow Control) Structured Programming (Flow Control)
Conditionals: Conditionals: If If/ /elseif elseif/else /else
s switch witch/c /case ase, try/catch , try/catch
Loops: Loops: while while, , error error, ,
for, break, for, break, 
return, continue return, continue
Slide reproduced from Selis Önel’s KMU206 lecture notes with permission
The   if…elseif structure
Note that indentation helps to make programs easier to read, esp. if you 
have long programs.
3
The   if…elseif structure

 If control_expr_1 is true (nonzero), then 
the program executes the statements in 
Block 1 and skips to the first executable 
statement following the  end.

 Otherwise, the program checks for the 
status of control_expr_2. If control_expr_2
is true (nonzero), then the program executes 
the statements in Block 2 and skips to the 
first executable statement following the end. 

 If all control expressions are zero,
then the program executes the statements in 
the block associated with the else clause.

 There can be any number of elseif 
clauses (0 or more) in an if construct, but 
there can be at most one else clause.
Example 3.2—The Quadratic Equation
Write a program to solve for the roots of a quadratic equation. The inputs 
required by this program are the coefficients a, b, and c of the quadratic eqn.
If b
2
-4ac > 0, two distinct real roots
If b
2
-4ac = 0, single repeated root
If b
2
- 4ac < 0, two complex roots
4
a = input ('Enter the coefficient A: ');
b = input ('Enter the coefficient B: ');
c = input ('Enter the coefficient C: ');
discriminant = b^2 - 4 * a * c;
if discriminant > 0
x1 = ( -b + sqrt(discriminant) )/( 2 * a );
x2 = ( -b - sqrt(discriminant) )/( 2 * a );
disp ('This equation has two real roots:');
fprintf ('x1 = %f\n', x1);
fprintf ('x2 = %f\n', x2);
elseif discriminant == 0
x1 = ( -b )/( 2 * a );
disp ('This equation has two identical real roots:');
fprintf ('x1 = x2 = %f\n', x1);
else
real_part = ( -b )/( 2 * a );
imag_part = sqrt ( abs ( discriminant ) )/( 2 * a );
disp ('This equation has complex roots:');
fprintf('x1 = %f +i %f\n', real_part, imag_part );
fprintf('x2 = %f -i %f\n', real_part, imag_part );
end
Try this !
Select your 
code with left 
click, then 
right click and 
select smart 
indent
Page 5


1
Structured Programming Structured Programming
KMU 255 KMU 255- - Computer Programming Computer Programming
Hacettepe University Hacettepe University
Department of Chemical Engineering Department of Chemical Engineering
2012 2012- -2013 Fall Semester 2013 Fall Semester
Dr. Eda Dr. Eda Ç Çelik elik- -AKDUR AKDUR
Structured Programming: 1 Structured Programming: 1- -Decisions Decisions
If condition
statements
end
2
Structured Programming (Flow Control) Structured Programming (Flow Control)
Conditionals: Conditionals: If If/ /elseif elseif/else /else
s switch witch/c /case ase, try/catch , try/catch
Loops: Loops: while while, , error error, ,
for, break, for, break, 
return, continue return, continue
Slide reproduced from Selis Önel’s KMU206 lecture notes with permission
The   if…elseif structure
Note that indentation helps to make programs easier to read, esp. if you 
have long programs.
3
The   if…elseif structure

 If control_expr_1 is true (nonzero), then 
the program executes the statements in 
Block 1 and skips to the first executable 
statement following the  end.

 Otherwise, the program checks for the 
status of control_expr_2. If control_expr_2
is true (nonzero), then the program executes 
the statements in Block 2 and skips to the 
first executable statement following the end. 

 If all control expressions are zero,
then the program executes the statements in 
the block associated with the else clause.

 There can be any number of elseif 
clauses (0 or more) in an if construct, but 
there can be at most one else clause.
Example 3.2—The Quadratic Equation
Write a program to solve for the roots of a quadratic equation. The inputs 
required by this program are the coefficients a, b, and c of the quadratic eqn.
If b
2
-4ac > 0, two distinct real roots
If b
2
-4ac = 0, single repeated root
If b
2
- 4ac < 0, two complex roots
4
a = input ('Enter the coefficient A: ');
b = input ('Enter the coefficient B: ');
c = input ('Enter the coefficient C: ');
discriminant = b^2 - 4 * a * c;
if discriminant > 0
x1 = ( -b + sqrt(discriminant) )/( 2 * a );
x2 = ( -b - sqrt(discriminant) )/( 2 * a );
disp ('This equation has two real roots:');
fprintf ('x1 = %f\n', x1);
fprintf ('x2 = %f\n', x2);
elseif discriminant == 0
x1 = ( -b )/( 2 * a );
disp ('This equation has two identical real roots:');
fprintf ('x1 = x2 = %f\n', x1);
else
real_part = ( -b )/( 2 * a );
imag_part = sqrt ( abs ( discriminant ) )/( 2 * a );
disp ('This equation has complex roots:');
fprintf('x1 = %f +i %f\n', real_part, imag_part );
fprintf('x2 = %f -i %f\n', real_part, imag_part );
end
Try this !
Select your 
code with left 
click, then 
right click and 
select smart 
indent
5
if constructs may be nested
But, for branches in which there are 
many mutually exclusive options, use 
a single if construct with multiple 
elseif clauses in preference to 
nested if constructs. It would be much 
easier…
The switch/case Construct
• If the value of switch_expr is equal 
to case_expr_1, then the first code 
block will be executed, and the 
program will jump to the first 
statement following the end of the 
switch construct. 
• Similarly, if the value of 
switch_expr is equal to 
case_expr_2, then the second code 
block will be executed, and the 
program will jump to the first 
statement following the end of the 
switch construct. 
• The otherwise code block, if 
present, will be executed whenever 
the value of switch_expr is outside 
the range of all of the case 
selectors.
Note that at most one code block can be 
executed. Thus if the switch expression 
matches more than one case expression, 
only the first one of them will be executed.