Thread: Strange String replacement...

Hello,

I'm not a C programmer for a long time (more than 8 years) and I don't know much more about the strings functions that we have today aside the basic ones...

I want to do some search/calculate/replace in a string but I don't know the functions well aside do in the hard code way, char by char... which I think should exist a better way to solve...

here's what I need:

I have a big string, and inside we have N times like this code:

"origin" "-264 -256 16"

the numbers aren't the same of course, and I need to replace all these origins in Z axis plus 15... (in this case, I need to add 15 to the 16 value)

so I need to turn that string into:

"origin" "-264 -256 31"

it's not always 2 chars, could be even like:

"origin" "-264 -256 1234"

but in all the cases is just add 15 to the Z axis to fix a bug.

so we need to get the number between the third space and third " after the string origin, convert to number, add 15, and replace in the string.

this must be done to all origins found on the string.

any ideas?

thanks a lot!

Sounds like something a regex library would be best able to do. Boost.Regex or Boost.Xpressive for example.

http://www.boost.org/

This is not very good, but heres an example I made that gets the index of the first space, and then the first " that comes after it. It would need some work to do what you want it to do, but its just to give a rough idea of how you can get these two indexes. (sorry its in C)

Code:

#include <stdio.h>

void GetSection(char*s)
{
     int count=0;
     int start_index=-1;
     int end_index;
     while(*s)
     {
              if(start_index == -1)
              {
                    if(*s == ' ')
                          start_index=count;
              }
              else if(*s == '"')
                      end_index=count;
              s++;  
              count++;        
     }
     printf("Start: &#37;i    End: %i", start_index, end_index);
}

int main()
{
    char str[]="dejfd siEUGH\"Fedfj";
    puts(str);
    GetSection(&str[0]);
    getchar();
}

Then you just need to split the string in three parts, convert the middle part to a number, add 15 to it, convert it back to a string, then concatenate the three strings.

Perhaps the least efficient way, but I think it oughta work:

Code:

void change_em(std::vector<std::string> & coords)
{
   std::stringstream s;
   int x, y, z;
   std::vector<std::string>::iterator it = coords.begin();

   while(++it != coords.end())
   {
     s.str(*it);
     s >> x >> y >> z;
     z += 15;
     s.str(std::string());  //in case z < 0 and + 15 makes for fewer digits
     s << x << y << z;
     *it = s.str();
     x = y = z = 0;
   }
}

If you just want the answer, and don't even care about what language it's written in, then use something like this

Code:

#!/bin/perl -w
use strict;
while ( <> ) {
    if ( /(.*?)(\d+)\"/ ) {
        print $1 . ($2+15) . "\"\n";
    }
}

I copy/pasted a couple of lines and got

Code:

$ perl foo.pl
"origin" "-264 -256 16"
"origin" "-264 -256 31"
"origin" "-264 -256 1234"
"origin" "-264 -256 1249"

take a look in this pseudocode:

Code:

while can find "origin" into String do {
   strReplaceFirst (String, origin, fhajas); // replace FIRST origin for fhajas in the string
   posA = find 3rd space after fhajas;
   posB = find next " after posA;
   Str1 = GetSubstring (String[0],posA);
   Str2 = GetSubstring (posB,String[size]);
   num = GetSubstring (posA, posB);
   ToNumber(num) += 15;
   String = Str1 + num + Str2;
}
strReplace (String, fhajas, origin) // replace ALL fhajas for origin in the string

could you write this in C++ to me?

feel free to suggest a better solution.

thanks a lot!

well, I realize that I can't change all origins, because I'll cause problems to other classes....
so I can only change info_player_deathmatch and info_player_start classes

so here the new pseudocode to solve this:

Code:

set working = 1;
while working == 1 {
	if "{" not found{
		set working = 0;
	else{
	 	subs = GetSubstring(String, first {, first });
		Str1 = GetSubstring (String[0], subs[0]);
		Str2 = GetSubstring (subs[size],String[size]);
		if found (info_player_deathmatch || info_player_start) in subs {
  			find "origin" location;
			posA = find 3rd space after origin location;
			posB = find next " after posA;
			Subs1 = GetSubstring (subs[0],posA);
			Subs2 = GetSubstring (posB,subs[size]);
			num = GetSubstring (posA, posB);
			ToNumber(num) += 15;
  			subs = Subs1 + num + Subs2;
			ReplaceAll (subs, {, [);
			ReplaceAll (subs, }, ]);
		}
	}
}
ReplaceAll (String, [, {);
ReplaceAll (String, ], });

any inputs?

You've got the pseudo-code, now go ahead and do it.

Or at least have a go at it.

Here's a list
http://cs.stmarys.ca/~porter/csc/ref...ib.html#string