string.c里的几个函数

char* strcpy(char* dest, const char *src)

{

char *temp = dest;

while(*src != '\0')

{

*dest = *src;

dest++;

src++;

}

*dest++ = '\0';

return temp;

}

char* strncpy(char *dest, const char *src, size_t n)

{

char *temp = dest;

while(*src != '\0' && n--)

{

*dest = *src;

dest++;

src++;

}

*dest++ = '\0';

return temp;

}

char *strcat(char* dest, const char* src)

{

char *temp = dest;

while (*dest)

dest++;

while(*src != '\0')

{

*dest = *src;

dest++;

src++;

}

*dest++ = '\0';

return temp;

}

int strcmp(const char* s1, const char* s2)

{

char res;

while (1)

{

res = *s1 - s2;

if(res != 0)

break;

}

return (int)res;

}