Answers for "how to replace an element in a string cpp"

c++ replace substrings

using namespace std;

string ReplaceAllSubstringOccurrences(string sAll, string sStringToRemove, string sStringToInsert)
{
   int iLength = sStringToRemove.length();
   size_t index = 0;
   while (true)
   {
      /* Locate the substring to replace. */
      index = sAll.find(sStringToRemove, index);
      if (index == std::string::npos)
         break;

      /* Make the replacement. */
      sAll.replace(index, iLength, sStringToInsert);

      /* Advance index forward so the next iteration doesn't pick it up as well. */
      index += iLength;
   }
   return sAll;
}


// EXAMPLE: in usage
string sInitialString = "Replace this, and also this, don't forget this too";
string sFinalString = ReplaceAllSubstringOccurrences(sInitialString, "this", "{new word/phrase}");
cout << "[sInitialString->" << sInitialString << "]n";
cout << "[sFinalString->" << sFinalString << "]n";

/* OUTPUT:
[sInitialString->Replace this, and also this, don't forget this too]
[sFinalString->Replace {new word/phrase}, and also {new word/phrase}, don't forget {new word/phrase} too] 
*/

string c++ replace

#include <cassert>
#include <cstddef>
#include <iostream>
#include <string>
#include <string_view>
 
std::size_t replace_all(std::string& inout, std::string_view what, std::string_view with);
std::size_t remove_all(std::string& inout, std::string_view what);
void test_replace_remove_all();
 
int main()
{
    std::string str{"The quick brown fox jumps over the lazy dog."};
 
    str.replace(10, 5, "red"); // (5)
 
    str.replace(str.begin(), str.begin() + 3, 1, 'A'); // (6)
 
    std::cout << str << "nn";
 
    test_replace_remove_all();
}
 
 
std::size_t replace_all(std::string& inout, std::string_view what, std::string_view with)
{
    std::size_t count{};
    for (std::string::size_type pos{};
         inout.npos != (pos = inout.find(what.data(), pos, what.length()));
         pos += with.length(), ++count) {
        inout.replace(pos, what.length(), with.data(), with.length());
    }
    return count;
}
 
std::size_t remove_all(std::string& inout, std::string_view what) {
    return replace_all(inout, what, "");
}
 
void test_replace_remove_all()
{
    std::string str2{"ftp: ftpftp: ftp:"};
    std::cout << "#1 " << str2 << 'n';
 
    auto count = replace_all(str2, "ftp", "http");
    assert(count == 4);
    std::cout << "#2 " << str2 << 'n';
 
    count = replace_all(str2, "ftp", "http");
    assert(count == 0);
    std::cout << "#3 " << str2 << 'n';
 
    count = remove_all(str2, "http");
    assert(count == 4);
    std::cout << "#4 " << str2 << 'n';
}