Annoying problem with string::find()

[Chris Mantoulidis]

I posted this here one day ago but it seems like it hasn't been put up
for some unknown reason. That gives me a chance to say things a bit
better in this post.

1st of all let's desribe the problem: In ParamGenerate() I want to
find all whitespaces before a certain point in one string. Thus I use
the string::find() function. However it seems like this function
ignores some whitespaces :/ This is really weird and I need your help.

Okay since the function ParamGenerate() itself isn't compilable, I
want to include the least compilable code which I wouldn't say is too
big But you gotta understand the purpose of my program so you can
understand better what I'm trying to do in ParamGenerate(). My program
will receive input in the following format:

[ <prefix> ] <COMMAND> <middle param> <middle param> ... <middle
param> <final param>

So the <prefix> is optional (and if inserted is a colon ':') and we
can have MANY <middle param>s (that must not include a colon ':' or a
space ' ') and just one <final param> (which starts with a ':' and can
contain spaces).

I just want to do that kind of seperation to my input with
ParamGenerate() (I remove the leading colon before calling
ParamGenerate()). However my ParamGenerate() seems to misfunction and
I think that this is caused by the find() function.

<btw> I have also tried implementing the ParamGenerate() function by
going through all the characters in the string and checking if they're
a space but I still have the same problem </btw>

<btw 2> Also in ParamGenerate() if I try to resize the vector to the
result of ParamCount() I get a segfault :/ This is the command I used:

params.resize(ParamCount(s));
</btw 2>

Here's the least compilable code:

#include <iostream>
#include <string>
#include <vector>

using namespace std;

string arg;
vector<string> params(1024);


/*
COMMAND IS LIKE
:user@host <CMD> <PARAMS>

and params are like

<PARAMS> = <MIDDLE PARAMS> <MIDDLE PARAMS> ... <MIDDLE PARAMS> <FINAL
PARAM>

middle params are params that contain no spaces or columns ':'

.... TO BE CONTINUED ...
*/


string RemoveLeadingColon(const string &s) {
string s2 = s;
if (s2[0] == ':') s2.erase(0,1);
return s2;
}

int ParamCount(const string &s) {
int count=1;
string::size_type i;
for (i=0; i < s.length(); i++) {
if (s == ' ' /*&& !found_column*/ )
count++;
else if (s == ':' /*&& !found_column*/ ) {
return count;
}
}
return count;
}

void ParamGenerate(const string &s) {
cout << "initializing vars...\n";
string::size_type first_column = s.find(':');
if (first_column == string::npos) first_column=s.length();
string::size_type white_space=0;
string::size_type last=0;
int curr_param=0;
cout << "starting search...\n";
while ((white_space = s.find(' ', white_space+1)) != string::npos &&
white_space <= first_column) {
cout << "found space...\n";
params[curr_param] = s.substr(last,white_space);
cout << "substring is \"" << s.substr(last,white_space) << "\"\n";
last=white_space+1;
curr_param++;
}
params[curr_param] = s.substr(first_column,s.length());
}

int main() {

cout << "gimme a cmd:\n";
getline(cin,arg,'\n');
cout << "you gave me: " << arg << "\n";

cout << "without leading ':' it is: " << RemoveLeadingColon(arg) <<
"\n";
ParamGenerate(RemoveLeadingColon(arg));
cout << "Params generated\n";

int what;
do {
cout << "tell me a num: ";
cin >> what;
if (what <= ParamCount(RemoveLeadingColon(arg)) && what >= 1)
cout << "param[" << what << "] = " << params[what-1] << "\n";
else
cout << "wrong index\n";
} while (what != 0);

return 0;

}

 

[Sharad Kala]

I posted this here one day ago but it seems like it hasn't been put up
for some unknown reason. That gives me a chance to say things a bit
better in this post.

I haven't delved a lot into your code.
I think perhaps this is an easier way to parse an input string.

#include<iostream>
#include<string>
#include<vector>
#include <sstream>
using namespace std;

template <class T>
vector<T> StringToVector( string& Str )
{
istringstream iss( Str );
return vector<T>( istream_iterator<T>(iss),istream_iterator<T>() );
}

int main(){
string str = " Here is a command ";
vector<string> vec(StringToVector<string>(str));
vector<string>::const_iterator itr;
for(itr = vec.begin(); itr!= vec.end (); ++itr)
cout << *itr; // Print Hereisacommand
}

Best wishes,
Sharad

 

[John Harrison]

I posted this here one day ago but it seems like it hasn't been put up
for some unknown reason. That gives me a chance to say things a bit
better in this post.

cout << "found space...\n";
params[curr_param] = s.substr(last,white_space);
cout << "substring is \"" << s.substr(last,white_space) << "\"\n";

You'll have better results with

params[curr_param] = s.substr(last,white_space - last);
cout << "substring is \"" << s.substr(last,white_space - last) << "\"\n";

but I wouldn't swear that your code doesn't have other bugs in it.

john

 

[Chris Mantoulidis]

I posted this here one day ago but it seems like it hasn't been put up
for some unknown reason. That gives me a chance to say things a bit
better in this post.

cout << "found space...\n";
params[curr_param] = s.substr(last,white_space);
cout << "substring is \"" << s.substr(last,white_space) << "\"\n";

You'll have better results with

params[curr_param] = s.substr(last,white_space - last);
cout << "substring is \"" << s.substr(last,white_space - last) << "\"\n";

but I wouldn't swear that your code doesn't have other bugs in it.

john

Oh so 2nd param in substr() is the length and not where the stop mark
is? Feh what a silly bug :/

I'll check out if I got more errors in my program in a min