C/C++ÓïÑÔÖÐÖ¸ÕëµÄÒâÒå
¿´µ½Õâ¸öÃæÊÔÌâ,¹À¼ÆºÜ¶à¸ÕѧCÖ¸ÕëµÄͬѧ¶¼»á¸ã´í.
void GetMemory(char *p)
{
// ´«µÝ½øÀ´µÄµÄֵʹµÃ*p==NULL
// ÕâÀïÐ޸ĵÄÊÇÕâ¸öº¯ÊýÄÚµÄÁÙʱָÕë±äÁ¿pµÄÖµ
p = (char *)malloc(100);
}
void Test(void)
{
char *str = NULL;
// ´«µÝ½øÈ¥µÄÊÇstrµÄÖµNULL
GetMemory(str);
// ÕâÀïstrÖ¸Õ벢δ¸³Öµ,ÈÔÈ»ÊÇNULL,ËùÒÔÕâÀ︳ֵ»á³ö´í
strcpy(str, "Hello World");
printf("%s\n", str);
free(str);
}
ÎÒÃÇÖªµÀ¼ÆËã»úÖ»ÈÏʶ0ºÍ1,ËùÓеÄÊý¾Ý,°üÀ¨Í¼Æ¬,ÎÄ×ÖµÈ×îÖÕ¶¼ÊÇת»»³É0ºÍ1À´±íʾ.
ΪÁË·½±ã˵Ã÷,ÎÒÃÇÓÃÊ®Áù¸ö¶þ½øÖÆÊý×é³ÉµÄÒ»¸öÊ®Áù½øÖÆÊýÀ´±íʾ.
ÔÚwin32ϵͳÖÐ,ÄÚ´æµØÖ·ÊÇ´Ó0µ½2^32bit(Ï൱ÓÚ0µ½4GB),win32ÖÐVC6.0ÖÐÖ¸Õë±¾ÖʾÍÊÇÒ»¸öÕ¼4¸ö×Ö½ÚµÄÎÞ·ûºÅÕûÐÎ(unsigned int),ÄÜÈ¡0µ½2^32ÖÐËùÓеÄÖµµÄÈÎÒ»¸öÖµ,¼´Ö¸ÕëÄÜÏò¼ÆËã»úÄÚ´æÖÐÈκÎÒ»¸öµØÖ·.
// pCharÖ¸ÏòµÄÒ»¸öcharÐͱäÁ¿(×¢Òâ×Ö·ûºÍ×Ö·û´®¸ÅÄîÇø·Ö¿ª)
char *pChar = NULL;
// pIntÖ¸ÏòµÄÊÇÒ»¸öintÐͱäÁ¿
int *pInt = NULL;
// pDoubleÖ¸ÏòµÄÊÇÒ»¸öpDoubleÐͱäÁ¿
double *pDouble = NULL;
struct node
{
int i, j, k;
};
// pNodeÖ¸ÏòµÄÊÇÒ»¸ö×Ô¶¨Òå½á¹¹Ìå±äÁ¿
struct node *pNode = NULL;
class TestClass
{
TestClass()
{
}
~TestClass()
{
}
};
// pClassÖ¸ÏòµÄÊÇÒ»¸ö×Ô¶¨ÒåÀà±äÁ¿
TestClass *pClass = NULL;
void Test(void)
{
printf("This is test function!\n");
}
typedef void (*pFunction)(void);
// pFunÖ¸ÏòµÄÊÇÒ»¸öTestÐͺ¯Êý
pFunction pFun = Test;
void Test1(void)
{
printf("sizeof(pChar)=%d\n", sizeof(pChar));
printf("sizeof(pInt)=%d\n", sizeof(pInt));
printf("sizeof(pDouble)=%d\n", sizeof(pDouble));
printf("sizeof(pNode)=%d\n", sizeof(pNode));
printf("sizeof(pClass)=%d\n", sizeof(pClass));
printf("sizeof(pFun)=%d\n", sizeof(pFun));
}
´òÓ¡µÄ½á¹ûÈçÏÂ:
sizeof(pChar)=4
sizeof(pInt)=4
sizeof(pDouble)=4
sizeof(pNode)=4
sizeof(pClass)=4
sizeof(pFun)=4
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