I was wondering how I could convert an int to a string and then add it to an existin string. i.e.
std::string s = "Hello";
//convert 1 to string here
//add the string 1 to s
I hope I'm making sense. Thank you very much in advance for any answer.
2 Answers
If the number you want to append is an integer or floating point variable, then use std::to_string and simply "add" it:
int some_number = 123;
std::string some_string = "foo";
some_string += std::to_string(some_number);
std::cout << some_string << '\n';
Should output
foo123
answered Jan 28, 2016 at 8:15
Some programmer dude
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3 Comments
KostasKol
I did that but I only get some random characters in the output. (% . , etc). (Along with the initial string of course)
Some programmer dude
@KostasKol Then you're doing something else wrong. The code in my answer works fine. If you don't get it to work, then create a Minimal, Complete, and Verifiable Example and show it in a new question, together with possible input, expected output and actual output.
KostasKol
could you believe I actually didn't see the <std::to_string(some_number)> part? I though I would just do <some_string += some_number>. It works! Thank you very much for the help.
The "modern" way is to use std::to_string(1). In fact, various overloads of std::to_string exist for different number types.
Putting this together you can write std::string s = "Hello" + std::to_string(1);
Alternatively you can use std::stringstream which can be faster due to fewer string concatenation operations which can be expensive:
std::stringstream s;
s << "Hello" << 1;
// s.str() extracts the string
1 Comment
KostasKol
Ok the std::to_string(1) did it. I also tried the stringstream one which seems better but I would have to make too many changes to my code just for one simple detail. At any rate, thank you very much. I really appreciate the help.
int i = 1; s.append(std::to_string(i));