c++ how to replace a string in an array for another string

Question

I am trying a short code that uses an array, I basically want to replace the word hate for love when I call my function WordReplace but I keep printing the same thing:

I don't love c++ I don't love c++

I have tried different things but I am not sure what is wrong

#include <iostream>
#include <string>
using namespace std;

void WordReplace(string*x, int start, int end, string g, string w)
{
   for (int z = start; z <= end; z++)
   {
      if (x[z] == g)
         x[z] == w;

      cout << x[z]<<" ";
   }
}

int main()
{
   string x[4] = {"I", "don't", "hate", "c++"};

   for (int i = 0; i < 4; i++)
   {
      cout << x[i] << " ";
   }
   cout << endl;

   WordReplace(x, 0, 3, "hate", "love");

   cout << endl;

   return 0;
}

x[z] == w should be x[z] = w. Read about the difference between = and == in your favorite C++ textbook. — Igor Tandetnik
– Igor Tandetnik, Commented Sep 7, 2017 at 15:02
It might also help to give your variable more intuitive names. At least g and w don't do it for me. But @IgorTandetnik has your answer. — Frecklefoot
– Frecklefoot, Commented Sep 7, 2017 at 15:06
I have tried different things -- Except the std::replace algorithm function, which does the job in one line of code. The point is that if you're writing code that has the feeling that it has to have been done millions of times before (like replacing x with y), then there is more than likely an STL algorithm function that does the job (if not a set of functions). — PaulMcKenzie
– PaulMcKenzie, Commented Sep 7, 2017 at 15:10
Actually gcc 5.1.0 does not produce any warnings. Reason seems to be that operator is overloaded. When std::string replaced with int warning "statement has no effect" is produced as expected. — Slava
– Slava, Commented Sep 7, 2017 at 15:26
Try using std::vector<std::string> instead of an array. A lot easier to pass to functions. — Thomas Matthews
– Thomas Matthews, Commented Sep 7, 2017 at 15:37

Slava · Accepted Answer · 2017-09-07 15:24:58Z

5

Just use std::replace:

std::string x[] = {"I", "don't", "hate", "c++"};
std::replace( std::begin( x ), std::end( x ), "hate", "love" );

live example

edited Sep 7, 2017 at 15:24

answered Sep 7, 2017 at 15:05

Slava

44.4k2 gold badges54 silver badges100 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

schorsch312 · Accepted Answer · 2017-09-07 15:10:45Z

You have c++. Use proper containers (e.g. std::vector).

#include <string>
#include <vector>
#include <iostream>
using namespace std;

void WordReplace(vector<string> &sentence, string search_string,
             string replace_string) {
    for (auto &word : sentence) {
        if (word == search_string)
            word = replace_string;
    }
}

int main() {
    vector<string> sentence{"I", "don't", "hate", "c++"};

    for (const auto word : sentence)
        cout << word << " ";
    cout << endl;

    WordReplace(sentence, "hate", "love");

    for (const auto word : sentence)
        cout << word << " ";
    cout << endl;

     return 0;
}

or even better, don't reinvent the wheel

std::vector<std::string> x {"I", "don't", "hate", "c++"};
std::replace( x.begin(), x.end(), "hate", "love" );

user8496745 · Accepted Answer · 2017-09-07 15:06:24Z

1

If you want to assign a new value to a variable you need the following syntax:

myVar = myValue;

This will change the value of myVar to myValue.

This construction:

myVar == myValue

is a comparison and is treated as a bool, since it returned true(if myVar equals myValue) and False (if they are not equal). The construction doesn't change the value of myVar or myValue.

In your case you need to replace x[z] == w by x[z] = w, as suggested by Igor

answered Sep 7, 2017 at 15:06

user8496745

Collectives™ on Stack Overflow

c++ how to replace a string in an array for another string

3 Answers 3

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related