I just wrote strcat( char*, char*) :)

#include<stdio.h>
char * strcat (char *,char *);
void main(void){
	char *s = "Pointer powers\n";
	char *t = " activate\n";
	
	char *z=strcat(s,t);

}
char * strcat(char *s, char *t){
	//return the concatenation of s and t
	char concatenation[255];
	int i=0;
	while (*s != '\0'){
		concatenation[i]=*s;
		*s++;
		i++;
	}
	while (*t != '\0'){
		concatenation[i]=*t;
		t++;
		i++;
	}
	concatenation[i]='\0';
	return concatenation;
}