sizeof 与 strlen

一、strlen
计算字符串的长度（不包括最后的'\0'），碰到第一个'\0'停止
eg：

#include <stdio.h>
#include <string.h>

int main()
{
    unsigned char *ucpStr = "ThisIsAStrlenTest";
    printf("strlen :%d\n",strlen(ucpStr));
    printf("Hello ,I'm LeTian!\n");
    while(1);
}

运行结果：
strlen :17
Hello ,I'm LeTian!

二、sizeof
返回变量或者类型在内存中占的字节数

#include <stdio.h>
#include <string.h>

typedef struct student
{
    unsigned char ucName;
    unsigned int uiNum;
    struct student *student1;
}t_STUDENT;

typedef unsigned int UINT32;

int main()
{
    unsigned int i = 0;
    unsigned char  c = 0;
    unsigned char *p =NULL;

    printf("sizeof i:%d\n",sizeof(i));
    printf("sizeof c:%d\n",sizeof(c));
    printf("sizeof p:%d\n",sizeof(p));

    printf("sizeof UINT32:%d\n",sizeof(UINT32));

    printf("sizeof t_STUDENT:%d\n",sizeof(t_STUDENT));

    printf("Hello ,I'm LeTian!\n");
    while(1);
}

运行结果：
sizeof i:4
sizeof c:1
sizeof p:4
sizeof UINT32:4
sizeof t_STUDENT:12
Hello ,I'm LeTian!

由结果可以看出（32-bit的处理器)
1)指针占4 Bytes
2）char型在结构中时占4 Bytes，在函数体中时为1 Byte