C 中的 string 操作（一）

#include

#include

typedef unsigned int size_t;

typedef char u8;

size_t my_strlen(const char *str)

{

size_t len = 0;

while (*str)

{

len++;

str++;

}

return len;

}

char *my_strcpy(char *pdst, const char *psrc)

{

printf("@%s()\n", __func__);

while ((*pdst++ = *psrc++));

return pdst;

}

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

{

printf("@%s()\n", __func__);

while (*s1 == *s2)

{

if ('\0' == *s1)

{

return 0;

}

s1++;

s2++;

}

return *s1 - *s2;

}

void *my_memcpy(void *pdst, const void *psrc, size_t num)

{

u8 *pd;

const u8 *ps;

pd = pdst;

ps = psrc;

printf("@%s()\n", __func__);

while (num > 0)

{

//*(char *)pdst++ = *ps++;

*pd++ = *ps++;

num--;

}

return pdst;

}

void *my_memset(void *buff, int c, size_t size_num)

{

size_t i;

char *ps = buff;

printf("@%s()\n", __func__);

for (i = 0; i < size_num; i++)

{

((char *)buff)[i] = c;

//*ps = c;

//ps++;

}

return buff;

}

int main(int argc, char *argv[])

{

const char *str = "hello";

char *cpto;

size_t len;

int i;

const char *str1 = "abc";

const char *str2 = "acb";

//memcpy

len = 3;

cpto = (char *)malloc(len);

my_memcpy(cpto, str, len);

printf("str = %s\n", cpto);

//strcpy

cpto = (char *)malloc(my_strlen(str));

my_strcpy(cpto, str);

printf("str = %s\n", cpto);

//strcmp

i = my_strcmp(str1, str2);

printf("The compare result is : %d\n", i);

//memset

//cpto = (unsigned char *)malloc(len * sizeof(int));

my_memset(cpto, 127, len);

for (i = 0; i < len; i++)

{

printf("%d\n", cpto[i]);

}

return 0;

}