[SOLVED] How to assign null values to an array in C++

newinubuntu · 05-07-2015, 02:20 PM

I wrote a program which concatenate additional character to a string in c++.

Code:

#include <iostream>
#include <string>
#include <cstring>

std::string interchange_merge( const char *s1, const char *s2 )
{
    std::string result;
    result.reserve( std::strlen( s1 ) + std::strlen( s2 ) );

    while ( *s1 && *s2 )
    {
        result.push_back( *s1++ );
        result.push_back( *s2++ );      
    }

    while ( *s1 ) result.push_back( *s1++ );
    while ( *s2 ) result.push_back( *s2++ );

    return result;
}

int main()
{
    char in[] = "ironman";
    char symbols[] = "*%#@^!";

    std::string s = interchange_merge( in, symbols );

    std::cout << s << std::endl; 
}

Output:

Quote:

i*r%o#n@m^a!n

So..now i want to write the reverse function of the above code..
That means,
INPUT:

Quote:

i*r%o#n@m^a!n

"*%#@^!" values should be null.
OUTPUT:

Quote:

ironman

Thankx in advance !!

NevemTeve · 05-07-2015, 02:29 PM

I don't get the 'values should be null' part, but if you want to remove every other character, then just do that:

Code:

void every_odd_char (const char *from, char *to)
{
    const char *p= from;
    const char *plim;
    char *q= to;

    if (!p) goto RETURN;
    for (plim= p + strlen (p); p<plim; p+=2) {
        *q++ = *p;
    }

RETURN:
    *q= '\0';
}

newinubuntu · 05-07-2015, 02:38 PM

Dear NevemTeve,

I am not getting very well..
If you don't mind..can you please put one function on my code which will do this task.
i apologize you because i know that asking for code is a invalid post..but i have no choice..please help me out !!

a4z · 05-08-2015, 01:07 AM

do you mean like this?

Code:

#include <iostream>
#include <string>
#include <cstring>

std::string interchange_merge( const char *s1, const char *s2 )
{
    std::string result;
    result.reserve( std::strlen( s1 ) + std::strlen( s2 ) );

    while ( *s1 && *s2 )
    {
        result.push_back( *s1++ );
        result.push_back( *s2++ );      
    }

    while ( *s1 ) result.push_back( *s1++ );
    while ( *s2 ) result.push_back( *s2++ );

    return result;
}

std::string everySecond(const std::string& in)
{
  std::string ret ;
  
  for (size_t i = 0 ; i < in.size() ; i+=2)
  {
    ret.push_back(in[i]) ;

  }

  return ret;
}



int main()
{
    char in[] = "ironman";
    char symbols[] = "*#@^!";


    std::string s = interchange_merge( in, symbols );

    std::cout << s << std::endl; 

    std::string s1 = everySecond(s);
    std::cout << s1 << std::endl; 
    
    size_t len = s.size() - s1.size() ;
    
    std::string s2(len, '0') ; // adopt to required
    std::cout << s2 << std::endl; 
}

i*r%o#n@m^a!n
ironman
000000

sundialsvcs · 05-08-2015, 08:04 AM

You see, one thing to be aware of ... and to fear ... about char foo[] = "bar";, is that you (only) get exactly enough bytes to store the value that you've specified. Very easy to scribble-over memory that way. Use strings. Use the actual string type.

newinubuntu · 05-08-2015, 12:35 PM

Dear a4z,
Thank you very much

Problem is solved.

I code it in another way just take a look:

Code:

#include <iostream>
#include <algorithm>
#include <string>

bool IsParenthesesOrDash(char c)
{
    switch(c)
    {
        case '~':  //~<@#$%^&*_+|:?!<
		case '<':
		case '@':
		case '#':
		case '$':
		case '%':
		case '^':
		case '&':
		case '*':
		case '_':
		case '+':
		case '|':
		case ':':
		case '?':
		case '!':
		case '>':
        return true;
    default:
        return false;
    }
}

int main()
{
    std::string str("1~9<2@.#3$.%0^.&1*2_8+|:?!<");
    str.erase(std::remove_if(str.begin(), str.end(), &IsParenthesesOrDash), str.end());
    std::cout << str << std::endl;
}

Quote:

output:192.3.0.128