Got stuck in C++ infinite loop

Question

I'm doing a leetcode challenge to practice my c++

I am supposed to replace all the "." from an ip address to "[.]"

so essentially, xxxx is supposed to become x[.]x[.]x[.]x

My code is:

#include <iostream>
#include <string.h>
 
using namespace std;
 
int main(int argc, const char * argv[]) {
    string address ="1.1.1.1";
    
    while(address.find(".") != string::npos){
        address.replace(address.find("."), 1,"[.]");
      
    }
    cout<<address<<endl;
}

However, I am getting stuck in a loop where it is doing:

xxxx

x[.]xxx

x[[.]]xxx

x[[[.]]]xxx

and so on.

How do I get out of this loop? Thank you!

Answer 1

You can specify where to start by the 2nd argument of std::string::find .

#include <iostream>
#include <string>
 
int main(int argc, const char * argv[]) {
    std::string address ="1.1.1.1";
    
    std::string::size_type start_pos = 0, current_pos;
    while((current_pos = address.find(".", start_pos)) != std::string::npos){
        address.replace(current_pos, 1,"[.]");
        start_pos = current_pos + 3; // start next search after the inserted string
      
    }
    std::cout<<address<<std::endl;
}

Answer 2

Learn to separate code into functions (this is important). Also it is easier to store result into separate variable, so you do not have to update search point.

std::string escapeDots(const std::string& s)
{
    std::string result;
    result.reserve(s.size() + 8);

    for (auto ch : s) {
        if (ch == '.') 
            result += "[.]";
        else
            result += ch;
    }
    return result;
}

This code is more clear the alternative answer and most probably is faster.

Answer 3

With <regex> , it would be

int main()
{
    std::string address = "1.1.1.1";
    
    std::cout << std::regex_replace(address, std::regex("\\."), "[.]") << std::endl;
}

Demo .