摘抄些微软实现的源码

来源：互联网发布：用友软件t3普及版编辑：程序博客网时间：2024/06/06 13:19

自己实现的感觉不怎么好，就在vc的安装文件中找到了这些微软的源码。

从细节上就能感受到大神的魅力。

int strcmp (const char * src,const char * dst)

{
int ret = 0 ;
while( ! (ret = *(unsigned char *)src - *(unsigned char *)dst) && *dst)
++src, ++dst;
if ( ret < 0 )
ret = -1 ;
else if ( ret > 0 )
ret = 1 ;
return( ret );
}

char *strcat (char * dst,const char * src)
{
char * cp = dst;
while( *cp )
cp++;
while( *cp++ = *src++ ) ;
return( dst );
}

char *strcpy(char * dst, const char * src)
{
char * cp = dst;
while( *cp++ = *src++ );
return( dst );
}

int strlen (const char * str)
{
const char *eos = str;
while( *eos++ ) ;
return( (int)(eos - str - 1) );
}

char *_strset (char * string,int val)
{
char *start = string;
while (*string)
*string++ = (char)val;
return(start);
}

char *strstr (const char * str1,const char * str2)
{
char *cp = (char *) str1;
char *s1, *s2;
if ( !*str2 )
return((char *)str1);

while (*cp)
{
s1 = cp;
s2 = (char *) str2;
while ( *s1 && *s2 && !(*s1-*s2) )
s1++, s2++;
if (!*s2)
return(cp);
cp++;
}
return(NULL);

}

int abs (int number)
{
return( number>=0 ? number : -number );
}

int memcmp (const void * buf1,const void * buf2,size_t count)
{
if (!count)
return(0);
while ( --count && *(char *)buf1 == *(char *)buf2 ) {
buf1 = (char *)buf1 + 1;
buf2 = (char *)buf2 + 1;
}
return( *((unsigned char *)buf1) - *((unsigned char *)buf2) );
}

void *memcpy (void * dst,const void * src,size_t count)
{
void * ret = dst;
while (count--) {
*(char *)dst = *(char *)src;
dst = (char *)dst + 1;
src = (char *)src + 1;
}
return(ret);
}

void *memset (void *dst,int val,size_t count)
{
void *start = dst;
while (count--) {
*(char *)dst = (char)val;
dst = (char *)dst + 1;
}
return(start);
}

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