void str_cat(char*p1,char*p2)
{
while (*p1 != '\0') p1++;
int i = 0;
while (p2[i++] != '\0')
{
*p1 = p2[i - 1];p1++;
}
*p1 = '\0';
}
int str_cmp(char*p1,char*p2)
{
while (*p1 != '\0' && *p2 != '\0')
{
if (*p1 != * p2) return *p1 - *p2;
p1++;p2++;
}
return *p1 - *p2;
}
int str_len(char*p1,char*p2)
{
int n = 0;
while (*p1 != '\0') { p1++; n++; }
while (*p2 != '\0') { p2++; n++; }
return n;
}
int main()
{
char s1[100]="hello ";
char s2[]="world!";
str_cat(s1, s2);
printf("%s\n", s1);
int n = str_cmp("aaa", "ab");
printf("%d\n", n);
n = str_len("aaa", "ab");
printf("%d\n", n);
}