std::string replace not retaining the end? - c++

Question

I want to replace a string within a string with *, using this code to replace everything between he and ld in helloworld:
#include <string>
#include <iostream>
int main()
{
const std::string msg = "helloworld";
const std::string from = "he";
const std::string to = "ld";
std::string s = msg;
std::size_t startpos = s.find(from);
std::size_t endpos = s.find(to);
unsigned int l = endpos-startpos-2;
s.replace(startpos+2, endpos, l, '*');
std::cout << s;
}
The output I got is He*****, but I wanted and expected He*****ld.
What did I get wrong?

Answer 1

You are replacing all the characters after index two. Count the indexes and replace only the range you want.
Try this:
#include <iostream>
#include <string>
int main ()
{
//this one for replace
string str="Hello World";
// replace string added to this one
string str2=str;
// You can use string position.
str2.replace(2,6,"******");
cout << str2 << '\n';
return 0;
}
First parameter for starting character
Second parameter for ending character
And Third parameter for string
There is a several ways you can do this. This is a one simple method.
UPDATE(After added your code):
Change:
unsigned int l=endpos-startpos-2;
s.replace(startpos+2,endpos,l,'*');
To:
unsigned int l=endpos-3;
s.replace(startpos+2,l,l,'*');
Because your endpos store position of character d. You need to substract 3 by endpos then l variable value become 7. After that in replace() change second parameter to l.
read more about replace().