CODEWITHSUNDEEP
c++string
jacksons123
jacksons123

Reputation: 181

Add a Character Between Strings in C++

So basically I'm trying to add a character in the middle of a string. Normally in something like Python, this would be pretty straightforward, but I'm really not sure how to achieve this in C++. What I'm trying to achieve is something like this: 

void converter(){
    converted = ":regional_indicator_" + character + ":";

}

So basically, I'm trying to add the variable character of a type char in a string. Should I be storing character as a string instead?

For reference here's all of my code:

#include <iostream>

using namespace std;

string inputLine;
char character;
string converted;

void input(){
    cout << "Please input the text in which you would like to be converted" << endl;
    cin >> inputLine;
}


void converter(){
    converted = ":regional_indicator_" + character + ":";

}
int main(){
    input();
    for (int i = 0; i < inputLine.length(); i++ ){
        character = tolower(inputLine[i]);
    }
    return 0;
}

Upvotes: 3

Views: 1047

Answers (4)

Sumit Jindal
Sumit Jindal

Reputation: 364

You can avoid invoking the std::string() constructor and memory allocation by using following. I have tested this before posting and it works:

void converter(){
    converted = ":regional_indicator_";
    converted.push_back(character);
    converted.push_back(':');
}

It's better because "converted" already will have some extra memory reserved, so you will just be filling that extra memory with two more characters and won't be allocating new memory.

Upvotes: 1

Galik
Galik

Reputation: 48655

The wasy way to build strings is to use a std::ostringstream like this:

void converter(){

    std::ostringstream oss;
    oss << ":regional_indicator_" << character << ":";

    converted = oss.str(); // copy the string out

    // ... etc ...
}

The added advantage of that method is it converts numbers to string automatically too.

That's not the fastest way so if speed was important I would take advantage of the static nature of this concatenation like this:

std::string converter(){

    static char* template = ":regional_indicator_X:";
    template[20] = character; // replace the `X` with your character
    converted.assign(template, 21); // assign your string all at once

    // ... etc ...
}

That works because your string is of fixed length. If thread safety is required you can use thread_local static char* template....

Upvotes: 0

Bernard
Bernard

Reputation: 5690

Append s behind the strings literals to treat them as std::strings instead of const char*s:

converted = ":regional_indicator_"s + character + ":"s;

You would need to do either using namespace std::literals or using namespace std::string_literals for it to work.

On a side note, in C++, it is strange to have a function converter() to modify a global variable using another global variable. You might want to consider passing character as a parameter to the function instead.

Upvotes: 3

Jesper Juhl
Jesper Juhl

Reputation: 31468

You can do it like this:

converted = ":regional_indicator_" + std::string(1, character) + ":";

This works because adding a string literal (const char *) to a string yields a string. But adding const char * and char results in pointer arithmetic. So, by constructing a std::string from "character" you end up with const char * + std::string yielding a string and then std::string + const char * again yields a string as the final result.

Upvotes: 2

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