Converting int to string

Question

Here str2 is a string I need to append and str1 is the string I append onto str2. After I append last to str2 I need to append a number (int cnt) to str2. So I am using the below code, which came to my mind and it is working. Is it wrong to code like this, since I saw the usage of string s = lexical_cast<string>(a); and itoa (i,buffer,10); implementations where compiler complaints about the library.

    string str2;
    string str1;
    int cnt;
    str2 += str1 ;
    str2 += char(cnt+48);//cnt converted to ASCII char and appended;

@FedericoReghenzani I went through the thread you suggested earlier, it does not discuss anything about code snippet shown here — ajax_velu, Aug 07 '14 at 20:02

score 5 · Accepted Answer · answered Aug 07 '14 at 20:00

5

This statement

str2 += char(cnt+48);

is bad. Firstly it uses magic number 48. It would be better to write at least as

str2 += char( cnt + '0' );

Secondly the code will work only if cnt contains a number with one digit.

It would be better to use standard function std::to_string For example

str2 += std::to_string( cnt );

answered Aug 07 '14 at 20:00

Vlad from Moscow

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Note that std::to_string was added in C++11! No mention of C++11 in tags or code. – Conduit Aug 07 '14 at 20:01
@Conduit I wonder, at what point will we be able to assume C++11 == C++. – zdan Aug 07 '14 at 20:07
@zdan Once all C++ code is converted, haha. Or, realistically, once compiling using the C++11 standard no longer requires flags, I guess? – Conduit Aug 07 '14 at 20:10
1

@zdan: Right now is probably about as close as it's ever going to get. If you're lucky, the question is already whether `C++` means `C++11` or `C++14`. – Jerry Coffin Aug 07 '14 at 20:29
std::stringstream is also useful and not dependent on C++11 and allows for cout style formatting – cppguy Aug 07 '14 at 20:58
@cppguy You are right. – Vlad from Moscow Aug 07 '14 at 21:24

score 0 · Answer 2 · answered Aug 07 '14 at 21:53

If you don't want to use c++11 and its std::to_string(...) you can use ostringstream class.

#include <iostream>
#include <sstream>

using namespace std;

int main()
{
    ostringstream ss;

    ss << 1;

    string str = ss.str();

    cout << str << endl;

    return 0;
}

Output:

Converting int to string

2 Answers2