How to sort each character string of character string array

Question

I want to sort each string of array of strings , here is my code that i tried.

#include <iostream>
#include <algorithm>

void _sort_word(char *str)
{
    int len = strlen(str); 
    std::sort(str,str+len); // program get stuck here. 
}
int main()
{
    char *str[] = {"hello", "world"};
    for(int i=0;i<2;i++){
        _sort_word(str[i]);
        cout << str[i] << "\n";
    }
}

I want to know is sort(str,str+len); a valid statement here, if not what should be done instead ?

The problem is that `std::sort()` needs write access the underlying memory, which currently is a char string literal and you can't change anything there. — πάντα ῥεῖ, Jun 22 '16 at 13:43
Can i somehow convert string literal to character array and send it to _sort_word() function ? — saurabh agarwal, Jun 22 '16 at 13:47
You need a better compiler or need to turn up your warnings: http://coliru.stacked-crooked.com/a/397b8016997e5c95 — NathanOliver, Jun 22 '16 at 13:47
@saurabhagarwal Try `char str[2][6] = {"hello", "world"};` if the max length is `6`. — songyuanyao, Jun 22 '16 at 13:49
Also see something about starting an [identifier with an underscore](http://stackoverflow.com/questions/228783/what-are-the-rules-about-using-an-underscore-in-a-c-identifier) — WhiZTiM, Jun 22 '16 at 13:50
Also, this cries for std::vector - is there a reason you try to avoid it? — lorro, Jun 22 '16 at 15:10
No, I am just trying to switch from c to c++. I am still unfamiliar with a lot of stuff. — saurabh agarwal, Jun 23 '16 at 04:03

score 6 · Accepted Answer · answered Jun 22 '16 at 13:56

First of all string literals in C++ have types of constant character arrays. So the correct array declaration will look like

const char *str[] = {"hello", "world"};
^^^^^

Thus the string literals pointed to by the elements of the array are immutable.

You should declare at least a two dimensional array.

Here is a demonstrative program

#include <iostream>
#include <algorithm>
#include <cstring>

void sort_word( char *s )
{
    size_t l = std::strlen( s ); 
    std::sort( s, s + l ); 
}


int main() 
{
    char str[][6] = { "hello", "world" };

    for ( auto &s : str ) sort_word( s );
    for ( auto &s : str ) std::cout << s << std::endl;

    return 0;
}

Its output is

ehllo
dlorw

If your compiler does not support the range based for statement then you can write instead

for ( size_t i = 0; i < sizeof( str ) / sizeof( *str ); i++ ) sort_word( str[i] );

How to sort each character string of character string array

1 Answers1