Computer programming chapter ( 4 )

LOGO

Prepaid By: Eng. Ibrahim Elewah

Higher Technological Institute 10th of Ramadan City6th of October Branch

Electrical and Computer Engineering Department

Main Reference

HTI Student Book and “C For Dummies”

by Dan Gookin 2nd Edition

Lecture Notes in

1

Course Contents

Introduction

C Programming Higher Technological Institute2

1

Program Development2

The Essential of C Programs3

Manipulating Data with Operators 4

Reading from and Writing to Standard I/O5

Decision6

Iteration7

Arrays8

C Functions9

Course Contents



Course Contents


Errors Types

Arithmetic Assignment Operators

Unary Minus Operator

The Cast Operator


Error Types


Syntax

Execution

Logic

Error Types

They are errors that youhave made in the form

Or syntax of the language

o Spelling a keyword incorrectly

o Errors that are detectedduring running of a programare shown in a dialog box thatappears and the error ishighlighted in the program.


Syntax

Example

Error Types

If the program has no syntax errors. The computer can execute it.

During execution, execution errors may be detected.

o If a number is divided by zerocauses an execution error.

Whenever an execution erroris detected, the computer displays adialog box with an error messageand stops executing the program.


Execution

Example

Error Types

If the output of the programdoes not agree with what isexpected, this is logic error.

The computer cannot detectsuch an error because it does notknow the logic of the programshould be.

So, it is your responsibility todetect logic errors in the program.


Logic

Error Types


Syntax

Execution

Logic

Arithmetic Assignment Operators

o Here the statement causes the value of the right-hand-operand to be assigned to the memory location of the left-hand-operand.

o Statement writes the value of the right-hand-operand (5) into the memory location of the integer variable a (which is the left-hand-operand in this case).


left-hand-operand = right-hand-operand

a=5 ;

b=a=5 ;

Assignment and Arithmetic Operators

Operator Description

+ = Addition Assignment Operator

- = Subtraction Assignment Operator

* = Multiplication Assignment Operator

/ = Division Assignment Operator

% = Remainder Assignment Operator


Equivalence of Statements

Statement Equivalence

x+ = y; x = x + y;

x- = y; x = x - y;

x* = y; x = x * y;

x/ = y; x = x / y;

x% = y; x = x % y;


z = z * x + y ; z *= x + y ; ?

Equivalence of Statements

Statement Equivalence

x+ = y; x = x + y;

x- = y; x = x - y;

x* = y; x = x * y;

x/ = y; x = x / y;

x% = y; x = x % y;


z = z * x + y ; z *= x + y ; ≠

Example# include <stdio.h> main ( ){ int x, y, z; x =1; y =3; z= 10;printf (“Given x = %d, y = %d, and z = %d,\n”, x, y, z);x= x + y;printf ( “ x= x +y assigns %d to x;\n”, x);x = 1; x+= y ; printf ( “ x+= y assigns %d to x;\n”, x);x = 1; z = z* x + y;printf ( “z = z*x+y assigns %d to z;\n”, z); z = 10; z = z* (x + y);printf ( “z = z*( x+ y) assigns %d to z;\n”, z);z = 10; z *= x + y;printf ( “z *= x+ y assigns %d to z;\n”, z);return 0; }


Unary Minus Operator

o Given an integer, you can get its negation by changing the sign of the integer by using, -, the minus operator, which is called the unary minus operator.

o Differ between the unary minus operator and the subtraction operator.

o The first – symbol is used as the subtraction operator while the second –symbol is the unary minus operator.


x = 1.234 ; -x equals -1.234

z = x- -y; OR z = x- (-y);

Incrementing or Decrementing by ONE


X++ ++X

X-- --X

IncrementP

ost-

Decrement

Pre

-

Example# include <stdio.h> main ( ){int x=5; printf (“ X++ %d ,\n”, x++);printf (“++X %d ,\n”, ++x);printf (“ X-- %d ,\n”, x--);printf (“ --X %d ,\n”, --x);return 0; }


Relational Operators

Operator Description

== Equal to

!= Not equal to

> Greater than

< Less than

>= Greater than or equal to

<= Less than or equal to


oAll relational expressions produce a result of either 0 or 1.

oGiven x = 3 and y = 5, for instance, the relational expression x < y gives a result of 1


x * y < z + 3 (x * y) < ( z + 3 )


Example# include <stdio.h> main ( ){ int x, y;

double z;

x = 7; y = 25; z = 24.46;

printf (“ Given x = %d, y = %d and z = %2f, \n”, x, y, z);printf ( “ x > = y produces: %d \n”, x > =y);printf ( “x = = y produces: %d \n”, x = =y);printf ( “x < y produces: %d \n”, x < y); printf ( “x > y produces: %d \n”, x > y);printf ( “x != y - 18 produces: %d \n”, x ! =y -18); printf ( “x + y ! = z produces: %d \n”, x +y ! = z); return 0; }


This is algebraically True and is supposed to return 1.

o However, the expression returns 0 which means that the equal to relationship does not hold.

o This is because the truncation of the integer division – that is , 1 /2 – produces 0 not 0.5.


1 / 2 + 1 / 2 = = 1 1 Or 0


The Cast Operator

o You can convert one data type to a different oneby prefixing and cast operator to the operand.

o The general form of the cast operator is

o Here data-type specifies the data type you wantto convert to x is a variable ( or, expression)that contains the value of the current data type.

o You have to include the parentheses (and) tomake up a cast operator.


(data-type) x

Example# include <stdio.h> main ( ){int x, y;

x = 7;

y = 5;

printf ( “ Given x = %d, y = %d, \n”, x, y);

printf ( “ x / y produces: %d \n”, x /y);

printf ( “(float) x / y produces: %f \n”, (float) x / y);

return 0 ;

}


LOGO

Eng. Ibrahim Elewah

Higher Technological Institute 10th of Ramadan City6th of October Branch

Electrical and Computer Engineering Department

24

Main Reference

HTI Student Book and “C For Dummies”

by Dan Gookin 2nd Edition

Computer programming chapter ( 4 )

Education

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