模拟实现memcpymemmove函数

Posted 2020-11-17 yishengpan

1、模拟实现memcpy

　　注意：将*dest =*src放在while判断里直接把*scr里面的 ‘‘ 一块拷贝过去了。

 1 #include<stdio.h>
 2 #include<assert.h>
 3 
 4 
 5 char* my_memcpy(char* dest, const char* src)
 6 {
 7     char* ret = dest;
 8     assert(dest != NULL);
 9     assert(src != NULL);
10     while (*dest++ = *src++)
11     {
12         ;
13     }
14     return ret;
15 }
16 
17 int main()
18 {
19     char arr[] = "abcdef";
20     my_memcpy(arr, "hello");
21     printf("%s
", arr);
22     system("pause");
23     return 0;
24 }

2、模拟实现mommove

 1 #include<stdio.h>
 2 #include<assert.h>
 3 
 4 char* my_memmove(char* dest, const char* src, size_t num)
 5 {
 6     char* ret = dest;
 7     assert(dest != NULL);
 8     assert(src != NULL);
 9     while (num--)
10     {
11         *dest++ = *src++;
12     }
13     return ret;
14 }
15 
16 int main()
17 {
18     char arr[] = "abcdhello";
19     my_memmove(arr, arr + 4, 4);
20     printf("%s
", arr);
21     system("pause");
22     return 0;
23 }