how to remove string from string?

Question

example
input
102030

output
123

input
10009

output
19

//string without space like the example

Answer 1

#include <iostream>
#include<cstring>
using namespace std;
int main() {
string str="1030012011"; //sample string
string res=""; //result string to be printed
for(int i=0;i<str.length();i++)
if(str[i]!='0')
{
res+=str[i];
}
cout<<res<<endl;
return 0;
}

//I am writing simple logic followed here :
1)make a string variable to print result
2)run a loop through each alphabet of string (though here its numbers)
3)whenever the alphabet is not '0' , then add that alphabet to res
4)print res

Answer 2

Oh😕yes I seeing,

Answer 3

You can do it in two ways

Removing from original string. This one you will do it more operations but spend less memory and you will lose original input.

Or

Removing using a empty auxiliary array adding the elements that no match your char.

Like this:

https://code.sololearn.com/cDxMj07PCV6R/?ref=app

In this case you do less operations but this costs more memory and you don't lose original input.