strcat()和strncat()函数的实现

#include<iostream>
#include<stdio.h>
#include<assert.h>

char *my_strcat( char *des,const char *src);
char *my_strcat(  char *des,const char *src)
{
assert(des != NULL || src != NULL);
char *addr = des;
while(*des != '\0')
{
++des;
}
while((*des++ = *src++) != '\0')
{
;
}
return addr;

}
int main()
{

char src[] = "liusenlin";
char des[]  = "liu";

char *result  = NULL;
result = my_strcat(des,src);
printf("%s \n",result);
return 0;
}

#include<iostream>
#include<stdio.h>
#include<assert.h>

char *my_strncat( char *des,const char *src,size_t len);
char *my_strcat(  char *des,const char *src,size_t len)
{
assert(des != NULL || src != NULL);
char *addr = des;
while(*des != '\0')
{
++des;
}
while(len-- && (*src) != '\0')
{
*des++ = *src++ ;
}
*des = '\0';
return addr;

}
int main()
{

char src[] = "liusenlin";
char des[]  = "liu";

char *result  = NULL;
result = my_strncat(des,src,2);
printf("%s \n",result);
return 0;
}