Can anyone suggest me a good blog for binary search on double ? I found these type of implementation on different blog but failed to manage explanation. Could anyone explain it ?

I found these type of implementation on different blog without explanation. Could anyone explain it ? Type 1:

include<bits/stdc++.h>
using namespace std;
//We want to find an element which a<0.0000001
const float target = 0.0000001;
int main() {  float l=0.00000000,r=100000.00000000;  cout << l << " " <0.0000000001){  float mid = (float)((l+r)/2);  cout << mid <target) r=mid;  else l=mid;  }cout << l; } Type 2:
int iterations = 0; while(iterations < 300) {  // your binary search logic  iterations++; }