#includechar *catstr(char *a,char *b){char *p=a,*q=b;while(*p) p++;while(*q)*p++=*q++;*p='\0';return a;}void main(){char s1[50]="abcdef";char s2[]="12345678890";printf("s1+s2=%s\n",catstr(s1,s2));}
