Exam 2 – Nov 18th

Room ACIV 008

Project 2 Update Your code needs to use loops to create the

multiplication table. Hint: use nested for loop (Lecture L14 slide 18)

Use loop structure to compute the power.

A Sample Program to Illustrate Switch-Case switch (grade) {

case ('a') :case ('A') :

printf ("Good Job!\n") ;brake;

case ('b') :case ('B') :

printf ("Pretty good.\n") ;brake;

A Sample Program to Illustrate Switch-Case

case ('c') :case ('C') :

printf ("Better get to work.\n") ;brake;

case ('d') :case ('D') :

printf ("You are in trouble.\n") ;brake;

default : printf ("You are failing!!\n") ; brake;

} /* End of switch-case structure */} /* End of main program */

Which Are Legal Identifiers? AREA area_under_the_curve 3D num45 Last-Chance #values x_yt3 pi num$ %done lucky***

Try them all in one of your the programs!!!

Logical Operators So far we have seen only simple conditions.

if ( count > 10 ) . . .

Sometimes we need to test multiple conditions in order to make a decision.

Logical operators are used for combining simple conditions to make complex conditions.

&& is ANDif ( x > 5 && y < 6 )

|| is OR if ( z == 0 || x > 10 )

! is NOTif ( ! (bob > 42) )

Arithmetic Expressions: True or False

Arithmetic expressions evaluate to numeric values.

An arithmetic expression that has a value of zero is false.

An arithmetic expression that has a value other than zero is true.

Practice with Arithmetic Expressions int a = 1, b = 2, c = 3 ; float x = 3.33, y = 6.66 ;

Expression Numeric Value True/False a + b 3 T b - 2 * a 0 F c - b – a 0 F c – a 2 T y – x 3.33 T y - 2 * x 0 F

Truth Table for &&Exp1 Exp2 Exp1 && Exp2

0 0 0

0 nonzero 0

nonzero 0 0

nonzero nonzero 1

Exp1 && Exp2 && … && Expn will evaluate to 1 (true) only if ALL subconditions are true.

Truth Table for ||Exp1 Exp2 Exp1 || Exp2

0 0 0

0 nonzero 1

nonzero 0 1

nonzero nonzero 1

Exp1 && Exp2 && … && Expn will evaluate to 1 (true) if only ONE subcondition is true.

Truth Table for !Expression ! Expression

0 1

nonzero 0

Some Practice Expressionsint a = 1, b = 0, c = 7;

Expression True/False

a 1 Tb 0 F

c 7 T

a + b 1 F

a && b T&&F F

a || b T || F T

!c 7 F

!!c 7 T

a && !b T && T T

a < b && b < c F && T F

a > b && b < c T && T T

a >= b || b > c T || F T

Preprocessor Directives Lines that begin with a # in column 1 are called

preprocessor directives (commands). Example: the #include <stdio.h> directive

causes the preprocessor to include a copy of the standard input/output header file stdio.h at this point in the code.

If we have #include <foo.h> the preprocessor will place the contents of the file foo.h into the code.

This header file was included because it contains information about the printf ( ) function that is used in this program.

Nested for Loopsfor ( i = 1; i < 5; i = i + 1 ){ for ( j = 1; j < 3; j = j + 1 ) {

if ( j % 2 == 0 ){ printf (“O”) ;}else{ printf (“X”) ;}

} printf (“\n”) ;}

How many times is the “if” statement executed?

What is the output ?

XOXOXOXO

15

Nested for Loops

int rows, columns; for (rows=1; rows<=5; rows++) {

for (columns=1; columns<=10; columns++){

printf("*");} printf ("\n");

}

Output:

**********

**********

**********

**********

**********

Inner Loop

Outer Loop

16

Nested for Loops, Example #2

int rows, columns;

for (rows=1; rows<=5; rows++) {

for (columns=1; columns<=rows; columns++){ printf("*");} printf("\n");

}

Output:

*

**

***

****

*****Outer Loop Inner Loop

Nested for Loopsint j, k;

for(j = 0; j < 8; j++)// { for(k = 0; k < 8 - j; k++) //draw MAX - j blanks { printf(" "); }

for(k = 0; k <= j; k++) //draw remaining j columns as x's { printf("x"); } printf("\n"); } printf("\n");

x xx xxx xxxx xxxxx xxxxxx xxxxxxx xxxxxxxx

The break Statement The break statement can be used in

while, do-while, and for loops to cause premature exit of the loop.

THIS IS NOT A RECOMMENDED CODING TECHNIQUE.

Example break in a for Loop#include <stdio.h>int main ( ){

int i ;for ( i = 1; i < 10; i = i + 1 ){

if (i == 5){ break ;}printf (“%d “, i) ;

}printf (“\nBroke out of loop at i = %d.\n”, i) ;

return 0 ;}

OUTPUT:

1 2 3 4

Broke out of loop at i = 5.

If brake was not there the output would have been

1 2 3 4 5 6 7 8 9

The continue Statement The continue statement can be used in

while, do-while, and for loops. It causes the remaining statements in the

body of the loop to be skipped for the current iteration of the loop.

THIS IS NOT A RECOMMENDED CODING TECHNIQUE.

Example continue in a for Loop#include <stdio.h>int main ( ){

int i ;for ( i = 1; i < 10; i = i + 1 ){

if (i == 5){ continue ;}printf (“%d ”, i) ;

}printf (“\nDone.\n”) ;

return 0 ;}

OUTPUT:

1 2 3 4 6 7 8 9

Done.

5

Note we used continue; to skip printing 5

Exam 2 – Nov 18th

Room ACIV 008