how do i add a int to a string

Question

i have a string and i need to add a number to it i.e a int. like:

string number1 = ("dfg"); int number2 = 123; number1 += number2;

this is my code:

name = root_enter; // pull name from another string. size_t sz; sz = name.size(); //find the size of the string. name.resize (sz + 5, account); // add the account number. cout << name; //test the string.

this works... somewhat but i only get the "*name*88888" and... i don't know why. i just need a way to add the value of a int to the end of a string

"i don't know why". The second parameter to resize is a char, and resize uses it repeatedly to fill in any extra space it creates at the end of the string. In your case account is equal to 56 (mod 256), so you've passed the character 8. — Steve Jessop
– Steve Jessop, Commented Mar 7, 2010 at 2:22

dirkgently · Accepted Answer · 2010-03-06 19:49:31Z

There are no in-built operators that do this. You can write your own function, overload an operator+ for a string and an int. If you use a custom function, try using a stringstream:

string addi2str(string const& instr, int v) { stringstream s(instr); s << v; return s.str(); }

"There are no in-built operators that do this." I am disappoint. Oh well, I guess they couldn't think of everything...

Bertrand Marron · Accepted Answer · 2010-03-06 19:50:28Z

Use a stringstream.

#include <iostream> #include <sstream> using namespace std; int main () { int a = 30; stringstream ss(stringstream::in | stringstream::out); ss << "hello world"; ss << '\n'; ss << a; cout << ss.str() << '\n'; return 0; }

Georg Fritzsche · Accepted Answer · 2010-03-06 19:52:08Z

You can use string streams:

template<class T> std::string to_string(const T& t) { std::ostringstream ss; ss << t; return ss.str(); } // usage: std::string s("foo"); s.append(to_string(12345));

Alternatively you can use utilities like Boosts lexical_cast():

s.append(boost::lexical_cast<std::string>(12345));

Brian R. Bondy · Accepted Answer · 2010-03-06 19:49:51Z

1

Use a stringstream.

int x = 29; std::stringstream ss; ss << "My age is: " << x << std::endl; std::string str = ss.str();

answered Mar 6, 2010 at 19:49

Brian R. Bondy

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1 Comment

cpx Over a year ago

or use ostringstream to be precise.

den bardadym · Accepted Answer · 2010-03-06 21:29:09Z

0

you can use lexecal_cast from boost, then C itoa and of course stringstream from STL

answered Mar 6, 2010 at 21:29

den bardadym

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