数组定义：

char acBuf[sizeof(TRANS_HEAD_S) + sizeof(USER_HEAD_S) + 4] = {0};

结构体定义：

typedef struct

{

int iOne;

int iTwo;

int iThr;

}TRANS_HEAD_S;

typedef struct

{

int iUser;

}USER_HEAD_S;

1、实现结果：

acBuf[0] = 11

acBuf[1] = 0

acBuf[2] = 0

acBuf[3] = 0

acBuf[4] = 12

acBuf[5] = 0

acBuf[6] = 0

acBuf[7] = 0

acBuf[8] = 13

acBuf[9] = 0

acBuf[10] = 0

acBuf[11] = 0

acBuf[12] = 14

acBuf[13] = 0

acBuf[14] = 0

acBuf[15] = 0

acBuf[16] = 15

acBuf[17] = 0

acBuf[18] = 0

acBuf[19] = 0

2、代码实现：

#include typedef struct

{

int iOne;

int iTwo;

int iThr;

}TRANS_HEAD_S;

typedef struct

{

int iUser;

}USER_HEAD_S;

int main()

{

char acBuf[sizeof(TRANS_HEAD_S) + sizeof(USER_HEAD_S) + 4] = {0};

TRANS_HEAD_S *pstTransHead = NULL;

USER_HEAD_S *pstUserHead = NULL;

int i=0;

int *pValue = NULL;

/*pstTransHead指针指向了acBuf的头*/

pstTransHead = (TRANS_HEAD_S *)acBuf;

pstTransHead->iOne = 11;

pstTransHead->iTwo = 12;

pstTransHead->iThr = 13;

/*pstUserHead指向了acBuf的第13个字节的头，因为结构体TRANS_HEAD_S是12字节*/

pstUserHead = (USER_HEAD_S *)&pstTransHead[1];

pstUserHead->iUser = 14;

/*pValue指向了acBuf的第17个字节的头，因为结构体TRANS_HEAD_S是12字节，USER_HEAD_S是4个字节*/

pValue = (int *)&pstUserHead[1];

(*pValue) = 15;

for(i = 0; i < sizeof(acBuf); i++)

{

printf("acBuf[%d] = %d\n", i, acBuf[i]);

}

return 0;

}

3、对代码【pstUserHead = (USER_HEAD_S *)&pstTransHead[1];】

的解释——结构体赋值给另一个结构体

#include typedef struct

{

int iA;

int iB;

int iC;

}TEST_S;

int main(void)

{

TEST_S t1,t2;

/*给t1结构体赋值*/

t1.iA = 11;

t1.iB = 12;

t1.iC = 13;

/*t1结构体赋值给t2结构体*/

t2 = t1;

printf("t2.iA=%d t2.iB=%d t2.iC=%d\n", t2.iA, t2.iB, t2.iC);

return 0;

}

结果显示：t2.iA=11 t2.iB=12 t2.iC=13

4、char类型指针指向int类型数值,取值结果显示

#include int main()

{

int i = 1561;

char c = 0;

c = (char)i;

printf("i=%d c=%hhu\n", i, c);

return 0;

}

结果显示是：i=1561 c=25

1561：是

25：是