#include #include using namespace std; unsigned l(const char * s); //strlen int strcmp(const char* s,const char *t); char * strcpy(char *d,const char *s); char * strcat(char *d,const char *s); //versions without copy char * strcpy2(char *d,const char *s); char * strcat2(char *d,const char *s); //other cstring functions char * strncpy(char *d,const char *s, size_t n); char * strncat(char *d,const char *s, size_t n); int strncmp(char *s,const char *t, size_t n); void * memcpy(void *d,const void *s,size_t n); int main() { char d[100]="Test"; char * ret; cout<<"Initial string: d = "< d = "< d = "< d = "< d = "< d = "< d = "< d = "<*t?1:strcmp(s+1,t+1); } char * strcpy(char *d,const char *s){ return copy(s,s+l(s),d),d; } char * strcat(char *d,const char *s){ return copy(s,s+l(s)+1,d+l(d)),d; } //versions without copy char * strcpy2(char *d,const char *s){ return *s?(*d=*s,strcpy2(d+1,s+1),d):(*d=0,d); } char * strcat2(char *d,const char *s){ return *d?(strcat2(d+1,s),d):strcpy2(d,s); } //other cstring functions char * strncpy(char *d,const char *s, size_t n){ return *s&&n?(*d=*s,strncpy(d+1,s+1,n-1),d):n?(*d=0,strncpy(d+1,s,n-1),d):d; } char * strncat(char *d,const char *s, size_t n){ return *d?(strncat(d+1,s,n),d):strncpy(d,s,n); } int strncmp(char *s,const char *t, size_t n){ return !*s&&!*t||!n?0:*s<*t?-1:*s>*t?1:strncmp(s+1,t+1,n-1); } void * memcpy(void *d,const void *s,size_t n){ //this works because char is of size 1 byte, which is the "scale value" of size_t (1 of size_t == 1 byte) return strncpy((char*)d,(const char*)s,n); }

strcat/strcmp/strcpy challenge