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Exam 2 – Nov 18th Room ACIV 008

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 ' ) :

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Exam 2 – Nov 18th Room ACIV 008

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  1. Exam 2 – Nov 18th Room ACIV 008

  2. 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.

  3. 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;

  4. 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 */

  5. 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!!!

  6. 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 AND if ( x > 5 && y < 6 ) || is OR if ( z == 0 || x > 10 ) ! is NOT if ( ! (bob > 42) )

  7. 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.

  8. Practice with Arithmetic Expressions • int a = 1, b = 2, c = 3 ; • float x = 3.33, y = 6.66 ; • ExpressionNumeric ValueTrue/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

  9. 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.

  10. 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.

  11. Truth Table for ! Expression ! Expression 0 1 nonzero 0

  12. Some Practice Expressions int a = 1, b = 0, c = 7; Expression True/False a 1 T b 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

  13. 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.hat 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.

  14. Nested for Loops for ( 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 ? XO XO XO XO

  15. Outer Loop Inner Loop Nested for Loops Output: ********** ********** ********** ********** ********** int rows, columns; for (rows=1; rows<=5; rows++) { for (columns=1; columns<=10; columns++) { printf("*"); } printf ("\n"); }

  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

  17. Nested for Loops x xx xxx xxxx xxxxx xxxxxx xxxxxxx xxxxxxxx int 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");

  18. 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.

  19. 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

  20. 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.

  21. 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

  22. Exam 2 – Nov 18th Room ACIV 008

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