标准strcpy函数
功能:复制字符串
参数:目的字符串指针,源字符串指针(输入参数)
返回:目的字符串指针
char * strcpy( char *strDest, const char *strSrc ) //将源字符串加const，表明其为输入参数
{
assert( (strDest != NULL) && (strSrc != NULL) ); //对源地址和目的地址加非0断言
if ( strDest == strSrc)
return strDest ;
char *address = strDest;
while( (*strDest++ = * strSrc++) != ‘/0’ );
return address; //为了实现链式操作，将目的地址返回
}
标准strlen函数
功能:计算字符串长度,结束符/0不计算在内
参数:字符串指针(输入参数)
返回:字符串长度 int
int strlen( const char *str )
{
assert( strt != NULL ); //断言字符串地址非0
int len;
while( (*str++) != '/0' )
{
len++;
}
return len;
}
char *strncpy(char *a, const char *b, size_t n)
{
/* is is quite likely that memcpy(a, b, MIN(n, strlen(b))
is now faster than this first bit: */
char *t = a;
char *t_end = a+n;
if (n > 0)
{
while (t < t_end && ((*t++ = *b++)))
{
;
}
/* pad with NULs if fewer than N characters */
while (t < t_end)
{
*t++ = '/0';
}
}
return a;
}
char *strcat(char *a, const char *b)
{
char *t = a;
while (*t)
{
t++;
}
while ((*t++ = *b++))
{
;
}
return a;
}
char *strncat(char *a, const char *b, size_t n)
{
char *t = a;
char *t_end;
while (*t)
{
t++;
}
/* append at most 'n' characters */
t_end = t+n;
while (t < t_end && (*t++ = *b++))
{
;
}
/* always NUL terminate, even if strlen(b) > n chars */
*t = '/0';
return a;
}
int strcmp(const char *a, const char *b)
{
while (*a)
{
if (*a != *b)
{
return (int)(*a) - (int)(*b);
}
else
{
a++;
b++;
}
}
return (*b ? -1 : 0);
}
int strncmp(const char *a, const char *b, size_t n)
{
while (n-- > 0)
{
if (*a != *b)
{
return (int)(*a) - (int)(*b);
}
else if (*a)
{
a++;
b++;
}
else
{
return 0;
}
}
return 0;
}
#endif /* OS_HOSTED */
int strncasecmp(const char *a, const char *b, size_t n)
{
while (n-- > 0)
{
if (toupper(*a) != toupper(*b))
{
return (int)(*a) - (int)(*b);
}
else if (*a)
{
a++;
b++;
}
else
{
return 0;
}
}
return 0;
}
int strnicmp(const char *a, const char *b, size_t n)
{
return strncasecmp(a, b, n);
}
int strcasecmp(const char *a, const char *b)
{
while (*a)
{
if (toupper(*a) != toupper(*b))
{
return (int)(*a) - (int)(*b);
}
else
{
a++;
b++;
}
}
return (*b ? -1 : 0);
}
标准空字符判断函数
/**
* 功能:空字符判断
* @c char.
* @return positive if c is space char
* negative and negative non-zero if not
**/
int isspace(char c)
{
return (c == ' ') || (c == '/t') || (c == '/n');
}
#define CHAR_BIT 8
#define CHAR_MAX 127
#define CHAR_MIN (-128)
#define INT_MAX (0x7fffffff)
#define INT_MIN (-INT_MAX - 1)
#define LONG_MAX (0x7fffffff)
#define LONG_MIN (0x80000000U)
#define SCHAR_MAX 127
#define SCHAR_MIN (-128)
#define SHRT_MAX (0x7fff)
#define SHRT_MIN (0xffff8000)
#define UCHAR_MAX 255
#define UINT_MAX (0xffffffff)
#define ULONG_MAX (0xffffffffU)
#define USHRT_MAX (0xffff)
#define U_SHRT_MAX USHRT_MAX
long strtol(const char *s, char **endp, int base)
{
unsigned char *p = (unsigned char *)s;
long rv = 0;
int sig = 1;
/* skip leading spaces */
while (isspace(*p))
{
p++;
}
/* check for sign */
if (*p == '-')
{
sig = -1;
p++;
}
/* zero base => look at first digit */
if (base == 0)
{
if (*p == '0')
{
p++;
if (*p == 'x' || *p == 'X')
{
p++;
base = 16;
}
else
{
base = 8;
}
}
else
{
base = 10;
}
}
else
{
/* base 16 is allowed an initial 0x */
if (base == 16)
{
if (p[0] == '0' && (p[1] == 'x' || p[1] == 'X'))
{
p += 2;
}
}
}
/* and we're off */
while (1==1)
{
int cv = 256;
if (isdigit(*p))
{
cv = *p - '0';
}
else if (islower(*p))
{
cv = *p - 'a' + 10;
}
else if (isupper(*p))
{
cv = *p - 'A' + 10;
}
if (cv >= base)
{
if (endp)
{
*endp = p;
}
return rv*sig;
}
else
{
p++;
rv = rv * base + cv;
if ((BITS)rv & 0x80000000U)
{
if (endp)
{
*endp = p;
}
ATMOS_SETERR(ERANGE);
return (sig == 1 ? LONG_MAX : LONG_MIN);
}
}
}
}
unsigned long strtoul(const char *s, char **endp, int base)
{
unsigned char *p = (unsigned char *)s;
unsigned long rv = 0;
/* skip leading spaces */
while (isspace(*p))
{
p++;
}
/* zero base => look at first digit */
if (base == 0)
{
if (*p == '0')
{
p++;
if (*p == 'x' || *p == 'X')
{
p++;
base = 16;
}
else
{
base = 8;
}
}
else
{
base = 10;
}
}
else
{
/* base 16 is allowed an initial 0x */
if (base == 16)
{
if (p[0] == '0' && (p[1] == 'x' || p[1] == 'X'))
{
p += 2;
}
}
}
/* and we're off */
while (1==1)
{
int cv = 256;
if (isdigit(*p))
{
cv = *p - '0';
}
else if (islower(*p))
{
cv = *p - 'a' + 10;
}
else if (isupper(*p))
{
cv = *p - 'A' + 10;
}
if (cv >= base)
{
if (endp)
{
*endp = p;
}
return rv;
}
else
{
p++;
if (rv & 0x80000000U)
{
if (endp)
{
*endp = p;
}
ATMOS_SETERR(ERANGE);
return ULONG_MAX;
}
rv = rv * base + cv;
}
}
}