strcpy

 1 #include<stdio.h>
 2 # include <stdlib.h>
 3 char *mystrncpy(char *dest,char *src,int n)
 4 {
 5     if(dest ==NULL|| src ==NULL)
 6     {
 7         return NULL;
 8     }
 9     while (*src !='\0'&&n>0)
10     {
11         *dest =*src;
12         dest++;
13         src++;
14         n--;
15     }
16     return dest;
17     
18 }
19 
20 char *mystrcpy(char *dest,char *src)
21 {
22     if(dest ==NULL|| src ==NULL)
23     {
24         return NULL;
25     }
26     while (*src !='\0')
27     {
28         *dest =*src;
29         dest++;
30         src++;
31     }
32     return dest;
33     
34 }
35 
36 
37 int main(void)
38 {
39     char dest [128]= {'\0'};
40     char *src = "this is a test";
41     //char *p;
42     //p=mystrcpy(dest,src);
43     //puts(dest);
44     mystrncpy(dest,src,4);
45     puts(dest);
46     return 0 ;
47 }