Control Flow

1
Control Flow
2
if/else if construct

• include ltstdio.hgt
• int main(void)
•     int number 75    int mark
•     printf("Your examination mark\n")    printf
  ("Enter your score, please\n")    scanf("d",ma
  rk)    if (mark gt number)            printf
  ("Incredible, you have passed with a
  merit\n")        else if (mark gt
  65)            printf("You have
  passed\n")         else         printf("You
  have failed\n")        return 0

3
switch

• The general form of a switch statement is
• switch (variable) case expression1 do
  something 1 break
• case expression2 do something
  2 break....default do default processing

4

• int main(void)    float numb1 0, numb2 0
        / the two numbers to work on /    int
  menu 1             / add or substract or
  divide or multiply /    float total
  0           / the result of the calculation
  /    char calType             / what type of
  calculation /
•     printf("Please enter in the first of the two
  numbers\n\t")    scanf("f", numb1)           
        / READ first number /
•     printf("\n\nPlease enter the second of the
  two numbers\n\t")    scanf("f", numb2)
                  / READ second number /
•     printf("\n\nWhat would you like to
  do?\n\n")    / WRITE instructions
  /    printf("\t1 add\n")    printf("\t2
  substract\n")    printf("\t3
  multiply\n")    printf("\t4 divide\n")
•     printf("\n\nPleas make your selection
  now\n\t")    scanf("d",menu)
                    / READ calculation type /
•     switch (menu)                  / select the
  type of calculation /        case 1 total
  numb1 numb2        calType ''
              / assign a char to symbolise
  calculation type /        break    case 2
  total numb1 - numb2        calType
  '-'        break    case 3 total numb1
  numb2        calType ''        break    c
  ase 4 total numb1 / numb2        calType
  '/'        break     default printf("Invalid
  option selected\n")        if (menu 3
  numb2 0)            / cannot divide by 0
  /        printf("\n\n\tYou cannot divide by
  0\n\n")
•               / display result to 2 decimal
  places /    printf("\n\n
  ")    printf("\n\n\t.3f c .3f .2f",
  numb1, calType, numb2, total)    printf("\n\n
  \n\n")
•     return 0

5
Loop constructs

• While
• For
• Do-while

6
Break

• breakis used to exit from a do, for, or while
  loop, It is also used to exit from a switch
  statement. An example of break in a loop is shown
  here
• while (x lt 100)    x get_new_x()    if
  (kbhit())
• break     / key hit on keyboard
  /    process(x)

7
continue

• continue is used to bypass portions of code in a
  loop and forces the conditional expression to be
  evaluated. For example, the following while loop
  will simply read characters from the keyboard
  until an M or F gender is specified
• include ltstdio.hgtinclude ltconio.hgtinclude
  ltstdio.hgtinclude ltctype.hgt
• int main(void)    char gender
•      while (gender getch())            i
  f (gender ! 'M' gender ! 'F'
  )                    printf("Incorrect gender,
  please type again\n")            continue     
     
•      break        return 0

8
Bitwise operators

• bitwise AND TRUE if both of its operands is
  TRUE
• bitwise inclusive OR TRUE if either or
  both of its operands is TRUE.
• bitwise exclusive OR TRUE only if just one
  of the operands is True
• ones compliment turns all zeros into ones,
  and ones into zeros

9
Bit Shifts

• Arithmetic shift
• Logical shift

right shiftgtgt
Left shift ltlt
Left shiftltlt
right shiftgtgt