1. Introduction to Computers and Programming Class 15 Introduction to C Professor Avi Rosenfeld

2. #include void main() { int num, tenthou, thou, hund, ten, one; printf("Please enter a number\n"); scanf("%d",&num); tenthou=num/10000; thou=(num%10000)/1000; hund=(num%1000)/100; ten=(num%100)/10; one=(((num%10000)%1000)%100)%10; printf("%d%d%d%d%d",tenthou,ten, hund, thou, one); }

3. #include void main() { int num, tenthou, thou, hund, ten, one; printf("Please enter a number\n"); scanf("%d",&num); one=num%10; /*gets the last digit */ num=num / 10; ten=num%10; num=num / 10; hund=num%10; num=num / 10; thou=num%10; num=num / 10; tenthou=num%10; num=num / 10; printf("%d%d%d%d%d",tenthou,ten, hund, thou, one); }

4. Understanding Repetition #include #define digits 7 void main() { int num, temp; printf("Please enter a number\n"); scanf("%d",&num); for (int i = 1; i <= digits; i++) { temp=num % 10; num = num / 10; printf("Digit #%d is %d\n", i, temp); }

5. #include void main() { float num, high, low; printf("Please type the first number "); scanf("%f",&num); high = low = num; /* new notation same as one two lines */ for (int i = 2; i <=10; i++) { printf("Please enter number #%d ",i); scanf("%f",&num); if (num>high) high = num; if (num<low) low = num; } printf("The highest was %f\n",high); printf("The lowest was %f\n",low); }

6. #include void main() { int size; printf("Please enter the size\n"); scanf("%d",&size); for (int i = 0; i < size; i++) { for (int j = 0; j <= i; j++) printf("*"); printf("\n"); }

7. #include /* The following program converts a number that the user enters from Celcius to Fahrenheit (decimals allowed). The correct formula is: F = 9/5 C + 32. If the user enters a value less than 0, the program should print, "Error". */ int main() { float Celcius; printf("Please enter a value in Celcius "); scanf("%f",&Celcius); if (Celcius < 0) printf("Error"); else printf("%f degrees Celcius is %f degrees fahrenheit", Celcius, 9/5 * Celcius + 32); return 0; }

8. Short Answer a. What is the value after the following statements? int x = 5; x -= 1+2 * 3 % 2; Answer:1 or 4 b. If x = 1 and y = 3, what does the following print? printf("%d", 2 * x++ + ++y + 1); Answer: 7 c. If a = 0 and b = 1, does the following expression in parentheses evaluate to true or false? ( !a && b ) Answer: T_____

9. Short Answer d. What will the following print: #include void main() { int x = 1, y = 2; if (x=2); printf("stage 1"); if (x == y) printf("stage 2"); }

10. Short Answer #include void main() { int x = 90; switch(x) { case 100: printf("Here "); case 90: printf("I "); case 80: printf("am "); break; default: printf("not! "); }

11. Character constant Characters are represented internally through int values. You can reference them by using single quotes around the character –E.g. ‘A’, ‘a’, ‘1’ or ‘\n’ What is actually happening is the computer stores these as numbers –The int value for ‘A’ is 65, and for ‘a’ it is 97, etc, See Appendix D, page 1198, in your text for a chart of the int values for each character

12. getchar() Function contained in stdio.h A function is like a small program other programs can use to perform actions (an example you’ve used is printf() ) getChar() returns an int code for a character typed on the standard input (the keyboard) char c; c = getchar() ;

13. How to print a char Can use printf with a format control string of %c. For example, printf( “ The character is %c\n ”, c ); Can use another function in stdio.h called putchar() For example, putchar( c ) ;

14. putchar() Prints a character to the standard output (screen) Is a function also referenced in stdio.h

15. Using getchar() example #include int main() { char c ; /* declare character variable */ /* read a character and store it in c */ c = getchar() ; /* print it twice, two different ways */ printf("%c\n", c ); putchar( c ) ; /* one character at a time so here ’ s the newline */ c = '\n' ; putchar( c ); } /* end program */

16. Char Input #include void main() { int count=0; char letter; printf("Please type some letters\n"); do { scanf("%s",&letter); if (letter=='a') count++; }while(letter != 'b'); printf("There were %d 'A's in the sentence\n",count); }

17. #include void main() { int count=0; char letter; printf("Please type some letters\n"); do { letter = getchar(); /*fflush(stdin);*/ if (letter=='a') count++; }while(letter != EOF); printf("There were %d 'a's in the sentence\n",count); }