CODEWITHSUNDEEP
c++string
user2684892
user2684892

Reputation: 37

Delete the last substring

I have a task. There are 2 strings: S and s. I need to remove the last substring of S, that is the same with s. For 

S = [123 234 789 123]
         s = [123]
    result = [123 234 789]

Upvotes: -1

Views: 88

Answers (4)

wu1meng2
wu1meng2

Reputation: 537

#include <iostream>
#include <string>

int main() {
  std::string S = "123xyzxyz1234";
  std::string s = "123";

  // The last instance of s starts from index p of S
  auto p = S.rfind(s);
  auto tail = S.substr(p + s.length());
  if (p != std::string::npos) {
    S.resize(p);
    S += tail;
  }
  std::cout << "S = " << S << std::endl;
}

The if statement guards against not found cases.

Upvotes: 2

Kariem
Kariem

Reputation: 780

#include <vector>
#include <algorithm>
#include <string>

using namespace std;

string removeLastSubstr(string S, string s)
{
    reverse(S.begin(), S.end());
    reverse(s.begin(), s.end());

    if (s.find(s) != string::npos)
        S = S.substr(S.find(s) + s.size(), S.size());

    reverse(S.begin(), S.end());
    return S;

}

Upvotes: 0

Steephen
Steephen

Reputation: 15824

If none of your character from second substring is not repeating again before the last part of your substring, this will work:

   std::string S ="123234789123";
    std::string s="123";
    auto it= S.find_last_of(s[0]);
    std::cout<<S.substr(0,it);

Upvotes: 0

therainmaker
therainmaker

Reputation: 4343

Since the code shown is independent of any implementation details, I will give the brief overview of how to do this.

string S,s; // I am assuming they contain the right data
int position = S.rfind(s);
string ans1 = S.substr(0, position);
string ans2 = S.substr(position + s.length());
return ans1 + ans2;

There might be off by one errors in the code above, and some safety checks may be required. But I'm leaving that to you.

Upvotes: 0

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