• If all operands are integers , the result is an integer.

• If any operand is a floating point or double precision , the result is a double precision number.

• Two binary arithmetic operator symbols must never be placed side by side. For example 5 * % 12  is invalid.

• All expressions enclosed within parentheses are evaluated first .For example (6+4) / ( 2 * 1 ) , the  6 + 4  and  2 * 1  are evaluated first , yielding  10 / 2  . The 10 / 2 is then evaluated to yield 2 .

• We can use parentheses inside parentheses  . The inner parentheses are evaluated first . For example ( 2 * ( 5+7) ) / 4  = ( 2 *12) / 4 = 24 / 4 =6

• Parentheses cannot be used to indicate multiplication . For example (3+1)(4+6) is invalid .  We must use the * operator . The correct expression is (3+1) * (4+6) .

• Operand : can be a single constant , single variable or valid combination of constants and variables.

• The space around the operator does not affect the calculation.

• The result of an arithmetic expression is never a floating point number because the computer temporarily converts all floating numbers to double precision numbers .

• Some languages have an exponentiation operator (typically ^ or **), but C doesn't. (To square or cube a number, just multiply it by itself.)

When applied to integers, the division operator / discards any remainder, so 1 / 2 is 0 and 7 / 4 is 1. But when either operand is a floating-point quantity (type float or double), the division operator yields a floating-point result, with a potentially nonzero fractional part. So 1 / 2.0 is 0.5, and 7.0 / 4.0 is 1.75.

The modulus operator % gives you the remainder when two integers are divided: 1 % 2 is 1; 7 % 4 is 3. (The modulus operator can only be applied to integers.)

Examples

17 % 2 = 8

17 % 2 = 1

12 % 3 =4

12 % 3 =0  ( No Remainder)

The minus sign used in front of a single numerical operand negates the number.

In the absence of parentheses ,expressions containing multiple operators are evaluated by the priority or precedence of each operator relative to all other operators .

Expressions containing operators with the same precedence are evaluated according to their associativity .

When two or more operators have the same precedence and participate next to each other in an expression, the evaluation conceptually proceeds from left to right. For example, 1 - 2 - 3 is equivalent to (1 - 2) - 3 and gives -4, not +2.

For example , in the expression 8 + 5 * 2 /  4 - 1 , the multiplication and the division operators are at higher precedence than + and - and they are of equal priority .

8+5 *2 /4 -1 =

8+10  /4 -1  =

8 + 2-1        =

10 -1           = 9

Increment operator (++)

    Can be used instead of c+=1

Decrement operator (--)

    Can be used instead of c-=1

Preincrement

    Operator is used before the variable (++c or --c)

1. Change the variable.

2. Then evaluate the expression.

Postincrement

    Operator is used after the variable (c++ or c--)

1. Executes the expression .

2. Then the variable is changed.

If c equals 5, then

  printf( "%d", ++c );

        Prints 6

  printf( "%d", c++ );

        Prints 5

In either case, c now has the value of 6

When variable not in an expression

Preincrementing and postincrementing have the same effect

++c;

printf( “%d”, c );

Has the same effect as

c++;

printf( “%d”, c );

Examples

#include <stdio.h> int main() { int c = 5; printf( "%d\n", c ); printf( "%d\n", c++ ); /* postincrement */ printf( "%d\n\n", c ); c = 5; printf( "%d\n", c ); printf( "%d\n", ++c ); /* preincrement */ printf( "%d\n", c ); return 0; /* successful termination */ }