Permutations of chars in string

Hello

I found this code on the internet

Code:

---

#include <iostream>
#include <string>

using namespace std;

int main()
{
        std::string default = "12345";

        int perm=1, digits=default.size();
        for (int i=1;i<=digits;perm*=i++);
        for (int a=0;a<perm;a++)
        {
                std::string avail=default;
                for (int b=digits,div=perm;b>0; b--)
                {
                        div/=b;
                        int index = (a/div)%b;
                        printf("%c", avail[index] );
                        //avail[index]=avail[b-1]; // fast but not lexigraphic order
                        avail.erase(index,1) ; // lexigraphic correct order
                }
                printf("\n");
        }
        printf("permutations:%d\n",perm);
        return 0;
}

---

But I am getting an error:

Code:

---

perm.cpp: In function ‘int main()’:
perm.cpp:8: error: expected unqualified-id before ‘default’
perm.cpp:10: error: expected primary-expression before ‘default’
perm.cpp:10: error: expected ‘,’ or ‘;’ before ‘default’
perm.cpp:14: error: expected primary-expression before ‘default’
perm.cpp:14: error: expected ‘,’ or ‘;’ before ‘default’
make[1]: *** [perm] Error 1
make: *** [run] Error 2

---

What is missing? Thanks a lot

Serge

This is exactly why you should try to write code instead of ^C + ^V.
'default' is a reserved word.
&& Try not to mix C and C++ io.
(btw...where is stdio.h ?)

Obviously this is C++ code..
Try to use C++ compiler. I copied ur code to my new project, it passed.

Quote:

---

Originally Posted by M1cKeY

Obviously this is C++ code..
Try to use C++ compiler. I copied ur code to my new project, it passed.

---

Here are the error messages from the Comeau online C++ compiler:

Code:

---

MODE:strict errors C++ C++0x_extensions

"ComeauTest.c", line 8: error: expected an identifier
          std::string default = "12345";
                      ^

"ComeauTest.c", line 10: error: expected an expression
          int perm=1, digits=default.size();
                            ^

"ComeauTest.c", line 14: error: expected an expression
                  std::string avail=default;
                                    ^

3 errors detected in the compilation of "ComeauTest.c".

---

Here are the error messages from g++ 4.4.5:

Code:

---

test.cpp: In function ‘int main()’:
test.cpp:8: error: expected unqualified-id before ‘default’
test.cpp:10: error: expected primary-expression before ‘default’
test.cpp:10: error: expected ‘,’ or ‘;’ before ‘default’
test.cpp:14: error: expected primary-expression before ‘default’
test.cpp:14: error: expected ‘,’ or ‘;’ before ‘default’
test.cpp:19: error: ‘printf’ was not declared in this scope
test.cpp:23: error: ‘printf’ was not declared in this scope
test.cpp:25: error: ‘printf’ was not declared in this scope

---

So yes, it is intended to be C++ code, but it isn't valid C++. Your compiler might allow the printf despite the missing #include <cstdio> because <cstdio> could have been included via <iostream>, but that does not mean that failing to #include <cstdio> is okay, as the error messages for g++ show. The use of default as a variable name is clearly an error, and allowing it could well be considered a bug with your compiler (or a non-standard "feature").