c++ string function

Question

i am trying to create a string function which is callable from the main function, however this gives segmentation fault... any ideas???

also is it possible to create a string function which returns a string..

#include <iostream>
#include <stdio.h>
#include <sstream>


using namespace std;

string callMe(string& k){

    cout << "String from callMe: " << k;

}


int main(){

   string k;

   k = "K SHK";

   cout << "String from main function: " << k << endl;

   callMe(k);

}

UPDATE:

its compiles fine..

[root@server dev]# ./stringtest 
String from main function: K SHK
Segmentation fault

Answer 1

your function callMe is expected to return a string, but you never return anything.

If you have compiler warnings enabled, you are warned about this ( i suggest adding -Wall and -Wextra)

It's resolvable be changing the return type from string to void .

The main function however does not need a return statement (but for beginners it may be better to just add return 0; ):

From the C++ standard:

A return statement in main has the effect of leaving the main function (destroying any objects with automatic storage duration) and calling std::exit with the return value as the argument. If control reaches the end of main without encountering a return statement, the effect is that of executing "return 0;"

Answer 2

The problem is that you have declared your function as returning a string , but don't return one.

There are two ways to fix it:

• If you didn't intend to return a string, change callMe to

  void callMe(string& k);

• If you did intend to return a string, then do so, by adding a return statement, eg

  return "I'm returned from callMe, called with " + k;

Additionally, some style comments:

• It is a good idea to initialize variables right at the point of definitions where possible. In your case you'd write:

   string k = "K SHK"; 

  or

   string k("K SHK"); 

  If you don't intend to modify the string afterwards, you might also consider to define is as const to catch accidental changes (eg by use of = instead of == ):

   string const k = "K SHK"; 

• If you don't change the argument in callMe , you should use a reference to const:

   void callMe(string const& k); 

  resp.

   string callMe(string const& k); 

This will allow you to call the function on constant strings and string literals, like callme("I'm a string literal");

Answer 3

void callMe(string& k){

    cout << "String from callMe: " << k;

}

Since you have declared Callme as a function that returns string, and on other side you are returning just nothing,such code can cause segmentation fault.(Since value in eax is undefined).

Answer 4

callMe（）和main（）函数必须返回某些内容...

Answer 5

In your function callMe there is no return . Try:

void callMe(string& k)
{
   cout << "String from callMe: " << k;
}

The main() function must return an int (usually 0).

Ps: If you don't modify the string k in your function, use a const reference const string& .

Answer 6

also is it possible to create a string function which returns a string.. Certainly. With a slight modification from your original code above it would look something like this...

string callMe(string& k){
    string returnValue("String from callMe: ");
    returnValue += k;
    cout << returnValue << endl;
    return returnValue;
}