#include<stdio.h>
int main()
{
int x=2,y,z;
x *=(y = z = 5);printf("%d\n”,x); //10 后面表达式的结果是5
z = 3;
x ==(y = z); printf("%d\n”,x); //10 只是判断，没有给x赋值
x =(y == z); printf("%d\n”,x); //1
x = (y&z); printf("%d\n”,x); //3 位与操作
x = (y&&z); printf("%d\n”,x); //1
y = 4;
x = (y | z); printf("%d\n”,x); //7 位或操作
x = (y || z); printf("%d\n”,x); //1
return 0;
}
#include<stdio.h>
main()
{
int b = 3;
int arr[] = {6,7,8,9,10};
int *ptr = arr;
*(ptr++)+=123; // arr[0]变成129，ptr指向arr[1]
printf("%d,%d\n",*ptr,*(++ptr));
}#include<stdio.h>
int main()
{
unsigned char a = 0xa5; //a中装着一个16进制数 二进制为：1010 0101
unsigned char b = ~a>>4; //a参与运算，自动转换为int，b的结果二进制为
//1111 0101
printf("a = %d\n",a); //a的十进制为165
printf("b = %d\n",b); //b的十进制为245
return 0;
}
int main()
{
unsigned int a = 0xCCCCCCF7;
unsigned char i = (unsigned char)a; //i中装着a的后两位，也就是F7
char* b = (char*)&a; //b指向a
printf("%08x,%08x",i,*b); //16进制输出，000000F7 ，FFFFFFF7
return 0;
}(x & (x-1) == 0) ? printf("yes\n") : printf("yes\n")#include<stdio.h>
main()
{
int count = 0;
int m = 9999;
while(m)
{
count++;
m = m&(m-1);
}
printf("%d\n",count); //8,进两次循环m的二进制去掉一位
}a = a + b; b = a - b; a = a - b; //还有更快的位操作版本： a = a ^ b; b = b ^ a; a = a ^ b;
#define S (365*24*60*60)
#define min((a), (b)) ((a)<(b))?(a):(b)
#include<stdio.h>
struct{
short a1;
short a2;
short a3;
}A;
struct{
long a1;
short a2;
}B;
int main()
{
char* ss1 = "0123456789";
char ss2[] = "0123456789";
char ss3[100] = "0123456789";
int ss4[100];
char q1[] = "abc";
char q2[] = "a\n";
char* q3 = "a\n";
char (*str1)[100] = (char(*)[100])malloc(100);
void* str2 = (void*)malloc(100);
printf("%d\n",sizeof(ss1)); //4
printf("%d\n",sizeof(ss2)); //11
printf("%d\n",sizeof(ss3)); //100
printf("%d\n",sizeof(ss4)); //400
printf("%d\n",sizeof(q1)); //4
printf("%d\n",sizeof(q2)); //3
printf("%d\n",sizeof(q3)); //4
printf("%d\n",sizeof(A)); //6 结构体都跟其中最大的的元素类型对齐
printf("%d\n",sizeof(B)); //16 跟long对齐，8*2
printf("%d\n",sizeof(*str1)); //100
printf("%d\n",sizeof(str2)); //4
return 0;
}
#include<stdio.h>
main()
{
char *a []={"hello","the","world"};
char **pa=a;
pa++;
printf(*pa); //the
}
#include<stdio.h>
int main()
{
int x=10,
y=10,
i;
for(i=0;x>8;y=i++)
{
printf("%d,%d",x--,y); //10, 10
return 0;
}
}typedef struct s {
int i;
int * p;
}S;
main()
{
S s; //定义一个结构体，其中有两个元素，i 和 *p
int *p = &s.i; //定义指针变量p，装着s中i的地址
p[0] = 4; //下标运算，在i中放入4
p[1] = 3; //在p中放入3
s.p = p; //把指针p中的地址，也就是s中i的地址给了s中的p
s.p[1] = 1; //下标运算，把s中的p的东西，也就是i的地址的下一位，也就是
//s中p装入一个1
s.p[0] = 2; //在这一行崩溃，p中装着一个常量，无法进行写操作
}原文：http://blog.csdn.net/x140yuyu/article/details/23618813