C++ Binary search algorithm to work like lower_bound -

i have question following previous -

i creating version of lower_bound binary search. binarysearch function find place insert new item , cycle move rest of array , insert right item can insert right position.

but following binarysearch function not work properly.

can see why?

bool creg::addcar ( const char *name){     carr * tmp = new carr(name); // item going insert     int pos = binarysearch(name,0,len); //len = number of items in array     checklen(); // whether have enough space move array right     if (length!=0)         (int = m_len; i>=pos; i-- )             arr[i+1] = spzarr[i];     arr[pos] = tmp;     length++;     checklen();     return true; }  int binarysearch(const char * name, int firstindex, int lastindex) {     if (lenght == 0) return 0; //number of items in array     if (firstindex == lastindex) return lastindex;     int tmp = lastindex - firstindex;     int pos = firstindex + tmp / 2; //position new item should go     if (tmp % 2)++pos;     if (lastindex == pos || firstindex == pos) return pos;     if (strcmp(name, arr[pos]) < 0) return binarysearch(name, firstindex, pos - 1);     if (strcmp(name, arr[pos]) > 0) return binarysearch(name, pos + 1, lastindex);     return pos;     } 

a fixed version of binarysearch

int binarysearch(const char* name, int firstindex, int lastindex) {     if (firstindex == lastindex) return lastindex;     int dist = lastindex - firstindex;     int mid = firstindex + dist / 2; //position new item should go     if (strcmp(name, arr[mid]) < 0) return binarysearch(name, firstindex, mid);     if (strcmp(name, arr[mid]) > 0) return binarysearch(name, mid + 1, lastindex);     return mid; } 

but may directly use std::lower_bound:

// assuming std::vector<std::string> arr;  void creg::addcar(const std::string& name) {     auto = std::lower_bound(arr.begin(), arr.end(), name);     arr.insert(it, name); }