1 Agenda - Loops while for for & while Nested Loops do-while Misc. & Questions.

Agenda - Loops

while for for & while Nested Loops do-while Misc. & Questions

Used to repeat the same instructions until a stop criterion is met

C provides some flexible ways of deciding how many times to loop, or when to exit a loop

for, while, do-while loops

while Loops

while (condition) {

statements;}

The statements are executed as long as condition is true

When the condition is no longer true, the loop “exits”

Example - Factorialint i, n, fact = 1;

printf("Enter a number\n");scanf("%d", &n);

i=1; while (i<=n) {

fact = fact*i;i = i + 1;

}printf("the factorial is %d\n", fact);

Example – Fibonacci Series

fibonacci.c

Fibonacci – step by stepfib1 = 0;fib2 = 1;

printf("%d ", fib1);

while(fib2 < lim){

printf("%d ", fib2);fib_next = fib1 + fib2;fib1 = fib2;fib2 = fib_next;

printf("\n");

Screen

fib2---

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib2---

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib2---

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2 3

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2 3

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2 3

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2 3

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2 3

Screen

fib_next

while(fib2 < lim){

printf("\n");

0 1 1 2 3

Screen

fib_next

Example – Integer Division

Input: Two integers – A and B

Output: How many times A contains B (it is

the result of the integer division A/B) Do not use the operators ‘/’, ‘*’ Solution: division.c

Solution

int a, b, res, tmp;

printf("Please enter two numbers.\n");scanf("%d %d", &a, &b);

tmp = a;res = 0;while(tmp >= b) {

tmp = tmp - b;res = res + 1;

printf("%d / %d = %d\n", a, b, res);

Example – Power of Two

Input: integer A Output: is there an integer N such

that A == 2^N? Solution: powerOfTwo.c

Solution

int a, tmp;

printf("Please enter a num\n");scanf("%d", &a);

tmp = a;while((tmp > 0) && (tmp % 2 == 0)) {

tmp = tmp / 2;}

if (tmp == 1) printf("%d is a power of two\n",a);

elseprintf("%d is NOT a power of two\n",a);

Agenda - Loops

for Loops

for (initiate; termination-condition; update) {body

1. Initiate2. If termination-condition holds:

a. Execute bodyb. Updatec. Go to step 2

Order of Executionfor ( i = 1; i<=10 ; i++) printf(“%d\n”, i);for ( i = 1; i<=10 ; i++) printf(“%d\n”, i);for ( i = 1; i<=10 ; i++) printf(“%d\n”, i); 1for ( i = 1; i<=10 ; i++) printf(“%d\n”, i);for ( i = 1; i<=10 ; i++) printf(“%d\n”, i);for ( i = 1; i<=10 ; i++) printf(“%d\n”, i); 2for ( i = 1; i<=10 ; i++) printf(“%d\n”, i);for ( i = 1; i<=10 ; i++) printf(“%d\n”, i); for ( i = 1; i<=10 ; i++) printf(“%d\n”, i); 3for ( i = 1; i<=10 ; i++) printf(“%d\n”, i); ……

Factorial (again)

int i, n, fact = 1;

printf("Enter a number\n");scanf("%d", &n);

for(i = 1; i <= n; i = i + 1)fact = fact * i;

printf("the factorial is %d\n", fact);

Factorial using for – step by step

#include <stdio.h>int main(void){ int i,n,fact = 1; printf("Enter a number\n"); scanf("%d", &n);

for(i=1;i<=n;i++) fact *= i;

printf("the factorial is %d\n", fact); return 0;}

Factorial using for – step by step

Factorial with for – step by step

Example: Fahrenheit to Celsius Conversion Table/* Print a Fahrenheit-to-Celsius conversion table

*/ int fahr;double celsius; int lower = 0, upper = 300;int step = 20;

for(fahr=lower ; fahr<=upper ; fahr = fahr + step) {celsius = 5.0*(fahr -32.0)/9.0;printf("%d\t%g\n", fahr, celsius);

Agenda - Loops

for while

for (initiate; termination-condition; update) {body;

initiate;while (termination-condition) {

body update;

When use for/while? Any for loop can be converted to while

loop and vice versa Some applications are more natural to

for, and others to while for is more suited when something is

performed a predefined number of times

while is more suited if the number of iterations is not known in advance (e.g., asking for legal input from a user)

Infinite Loops

What are they? Beware of them

‘break’ in Loops

When break is encountered, the loop exits regardless of whether the condition’s state

The program then continues to run from the first line after the loop

If called within a nested loop, break breaks out of the inner loop only

‘continue’ in Loops

When continue is encountered, the rest of the current’s loop’s iteration is ignored

The program then continues to run from the beginning of the loop

Agenda - Loops

Example: Rectangle of ‘*’/* Print a rectangle of *. The height and width are defined

by the user */int i,j;int height, width;

printf("Please enter the two box dimensions: \n");scanf("%d%d",&height,&width);

for (i = 1; i <= height; i++) {for(j = 1; j <= width; j++) {

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

Example

Write a program that accepts a number from the user, and prints out all of the prime numbers up to that number (Hints: nested loops, part of the solution was seen during lecture)

Solution (listprimes.c)int i, j, last;

printf("enter a number\n");scanf("%d", &last);for(i = 2; i <= last; i = i + 1) {

for(j = 2 ; j < i; j = j + 1) {if (i % j == 0) {

// i is not a primebreak;

}}if (j == i) {

// j "passed" all test and thus is a primeprintf("the number %d is prime\n", i);

Exercise

Change the former prime-listing program, so that is displays only the largest prime number which is smaller than or equal to the user’s input

Solution 1 (largest_prime.c)int i, j, last;int found = 0; /* This indicates whether we found the largest

prime */

printf("enter a number\n");scanf("%d", &last);i = last;while (!found) {/* Loop until we find the required prime */

for (j = 2 ; j < i; j = j + 1) if (i % j == 0) break;

if (j == i) /* If this is true then i is prime */ found = 1;else i--;

}printf("The largest prime not larger than %d is %d.\n", last, i);

Solution 2 (largest_prime_2for.c)

int i, j, last;printf("enter a number\n");scanf("%d", &last);for(i = last; i > 1; i = i - 1) {

for(j = 2 ; j < i; j = j + 1) if (i % j == 0) break; // inner loop

if (j == i) /* i is prime */ break;

}printf("The largest prime not larger than %d is %d.\n", last, i);

Exercise

Write a program that prints an upside-down half triangle of *.

The height of the pyramid is the input.

Solution (triangle.c) #include<stdio.h>

int main(void){

int i, j, size;

printf(“Please enter a size:\n”);scanf(“%d”,&size);for (i = 1; i <= size; i++){

for(j = i; j <= size; j++)printf("*");

printf("\n");}

return 0;}

Agenda - Loops

do-while Loops

do {body

} while (condition);

Similar to while loops Except the condition is evaluated after the

loop body The loop body is always executed at least

once, even if the expression is never true

Example: wait for legal input

int i;

printf("Please enter a positive number.\n");do { scanf("%d", &i); if (i <= 0) {

printf("That's not a positive number! Try again.\n");

}} while (i<=0);/* The program continues.... */

Agenda - Loops

getchar getchar() gets a single character from

the user. Requires including stdio.h Returns a non-positive number on

failure. Similar to scanf.

char c;

c = getchar();

char c;

scanf(“%c”, &c);

putchar

putchar(‘char’) prints out the character inside the brackets.

Requires including stdio.h Similar to printf.

char c;

putchar(c);

char c;

printf(“%c”, c);====

More Operators

Used as a short-hand for incrementing (or decrementing) variables.i++ or ++i == i = i + 1i-- or --i == i = i – 1i += a == i = i + ai -= a == i = i - ai *= a == i = i * ai /= a == i = i / a

Q1:עיינו בקטע הבא וסמנו את כל התשובות הנכונות

int k = 10, sum = 0;int j;for (j = 0;j < k; j = k - 1)

sum = sum + 1;

a. After execution the value of k is 10b. This code will fail in compilationc. After execution the value of j is 9 d. There will be an infinite loope. Non of these answers is correct

int sum = 0,number;for (number = 1;number <= 10; number = number

+ 1)number = number - 1;

printf(“%d”,sum);

a. This code will fail in compilationb. 0 will be printedc. 55 will be printedd. 45 will be printede. Non of these answers is correct

int i;for (i = 0; i < 10; i = i + 1)

for (i = 0; i < 9; i = i + 1)System.out.println(“*”);

a. 90 ‘*’ will be printedb. There will be an infinite loopc. 10 ‘*’ will be printedd. This code will fail in compilatione. Non of these answers is correct

Using the Debugger

1 Agenda - Loops while for for & while Nested Loops do-while Misc. & Questions.

Documents

Transcript of 1 Agenda - Loops while for for & while Nested Loops do-while Misc. & Questions.

Two-Dimensional Arrays and Nested Loops – part 6

1 Agenda Summary of last class Loops Simple Loops WHILE Loops FOR Loops Records Cursors.

COMPLEX SYSTEMS: Artificial Life, Culture & Evolutionng46/000-2015-Fall-ALICE...switch statements if/else commands while loops do-while loops for loops nested for loops break statement

Outlines Chapter 3 –Chapter 3 – Loops & Revision –Loops while do … while – revision 1.

1.6 Loops academy.zariba.com 1. Lecture Content 1.While loops 2.Do-While loops 3.For loops 4.Foreach loops 5.Loop operators – break, continue 6.Nested.

L16. Cell Arrays Set-Up Subscripting Nested Loops String Manipulations.

NESTED-LOOPS TILING FOR PARALLELIZATION AND LOCALITY ... · Computing and Informatics, Vol. 36, 2017, 566{596, doi:10.4149/cai 2017 3 566 NESTED-LOOPS TILING FOR PARALLELIZATION AND

Algorithms Design for the Parallelization of Nested Loops · Algorithms Design for the Parallelization of Nested Loops Outline Introduction What is Parallel Processing? Motivation

Tutorial_ for Loops and While Loops - National Instruments

Iterative Control: Nested Loops

Repetition Structures Chapter 5 5-1. Chapter 5 Objectives The Loop Instruction The While Instruction Nested Loops 5-2.

Adaptive Cyclic Scheduling of Nested Loops

Building Horizontal Loops and Nested Repeated Regions

Chapter 5 Loops, Printf Statements, Nested Control Statements and GUI Input & Output Section 1 - While Loops Section 2 - Printf Statements Section 3 -

Karel The Robot Nested If Statements While Loops Copyright © 2008 by Helene G. Kershner.

1 Flow of Control True and False in C Conditional Execution Iteration Nested Code(Nested-ifs, Nested-loops) Jumps.

Nested Loops – part 3

Chapter 5amanno/Chapter_05 Repetition Structures.pdf · Chapter 5 Objectives The Loop Instruction The While Instruction Nested Loops 5-2

Chapter 6 Boolean Variables & Nested Loops

Conditional loops while do while Counting loops for loops Arrays Recursion.