1. post-increment and pre-increment 的区别
来源：http://www.c4learn.com/c-programming/c-increment-operator/
#include<stdio.h>
void main()
{
int a,b,x=10,y=10;
a = x++;
b = ++y;
printf("Value of a : %d",a);
printf("Value of b : %d",b);
}
Different Types of Increment Operation
In C Programming we have two types of increment operator i.e Pre-Increment and Post-Increment Operator.
A. Pre Increment Operator
Pre-increment operator is used to increment the value of variable before using in the expression. In the Pre-Increment value is first incremented and then used inside the expression.
b = ++y;
In this example suppose the value of variable ‘y’ is 5 then value of variable ‘b’ will be 6 because the value of ‘y’ gets modified before using it in a expression.
B. Post Increment Operator
Post-increment operator is used to increment the value of variable as soon as after executing expression completely in which post increment is used. In the Post-Increment value is first used in a expression and then incremented.
b = x++;
In this example suppose the value of variable ‘x’ is 5 then value of variable ‘b’ will be 5 because old value of ‘x’ is used.