1. Flow of Control

2. Flow of Control C is a sequential language
statements in a program are executed one after another
To change flow of control, use
choice instructions: if, switch
iterative instructions: while, for
OR recursion
you may need operators

3. Operators for them < > <= >= == != Relational Operators
1 if the specified relationship is true, and 0 if false.
i < 7
>
j > 5
<=
k <= 4
>=
p >= 3
== 
if (x == 4) evaluates to true (or 1) if x is equal to four.
if (x = 4) is taken to be true because (x = 4) evaluates to a nonzero value (4). The expression also assigns the value 4 to x. !=
nChoice != 'Y'
TRUE means any value other than 0

4. Relational Operators Expressions Evaluates as (3 == 3) && (4 != 3)
(3 == 3)  && (4  !=  3)
True (1) because both operands are true
(4 > 2) || (7 < 11)
True (1) because (either) one operand/expression is true
(3 == 2)  &&  (7 == 7)
False (0) because one operand is false
 ! (4 == 3)
True (1) because the expression is false
NOT(FALSE) = TRUE
NOT(TRUE) = FALSE
The logical OR (||) should not be confused with the bitwise OR (|) operator. For example:
   1 || 4 evaluates to 1 (or True || True = True) while    1 | 4 (0001 | 0100 = 0101) evaluates to 5

5. some trivial examples

6. some tricky examples

7. short-circuit the evaluation stops as soon as the outcome is known
expr1 && expr2
if expr1 is evaluated to be false, expr2 needs not be evaluated
expr 1 || expr 2

8. The Compound Statement
A compound statement is a series of declarations and statements surrounded by braces { }
{ int a, b, c;
a += b += c;
printf (“a = %d, b = %d, c = %d\n”, a, b, c); }
a compound is usually called “block”
expression statements
a + b + c;
; /* empty statement */

9. if statement if (expr) (then) statement | block
statement can be an empty one
same for else statement

12. Iterative Statements while, for, and do statements
provide iterative action
goto, break, continue, return statements cause an unconditional transfer
SE people hate these (except return)

14. for statements comma operators
for ( sum = 0, i = 1 ; i <= n ; ++I )
sum += i;
for (sum = 0, i = 1 ; i <= n ; sum += i, ++i)

15. do statement a variant of while statement do { statements } while expr
the block is executed first, and then the expr is evaluated
you should be able to convert do statement to while statement, and vice versa

17. goto statement jump to a label it is considered harmful, but .....
goto label;
label: /* label is an identifier */
it is considered harmful, but .....

19. break statement
an exit from a loop

20. continue statement
stop the current iteration and goto the next iteration

21. switch statement

22. conditional operators
x = (y < z) ? y : z
if (y < z) x = y;
else x = z;
equals