Here, the operators +, - and * performed normally as you expected. In normal calculation, 9/4 equals to 2.25. But, the output is 2 in this program. It is because, a and b are both integers. So, the output is also integer and the compiler neglects the term after decimal point and shows answer 2 instead of 2.25. And, finally a%b is 1,i.e. ,when a=9 is divided by b=4, remainder is 1.
Suppose a=5.0, b=2.0, c=5 and d=2
In C programming,
a/b=2.5
a/d=2.5
c/b=2.5
c/d=2
Note: % operator can only be used with integers.
Increment and decrement operators
In C, ++ and -- are called increment and decrement operators respectively. Both of these operators are unary operators, i.e, used on single operand. ++ adds 1 to operand and -- subtracts 1 to operand respectively. For example:
Let a=5 and b=10
a++; //a becomes 6
a--; //a becomes 5
++a; //a becomes 6
--a; //a becomes 5
Difference between ++ and -- operator as postfix and prefix
When i++ is used as prefix(like: ++var), ++var will increment the value of var and then return it but, if ++ is used as postfix(like: var++), operator will return the value of operand first and then only increment it. This can be demonstrated by an example:
#include <stdio.h>
int main(){
int c=2,d=2;
printf("%d\n",c++); //this statement displays 2 then, only c incremented by 1 to 3.
printf("%d",++c); //this statement increments 1 to c then, only c is displayed.
return 0;
}