Removing whitespace

[fafner]

Im trying to parse user input and remove unnecessary whitespace. This is my code:

void parseInput(std::string *in) {
	for (int i = 0; i < in->length(); i++) {
		if (in->at(i) >= 'a' && in->at(i) <= 'z') {
			in->at(i) -= ('a' - 'A');
		}
		if (in->at(i) == ' ' && in->at(i-1) == ' ') {
			in->erase(i, 1);
			--i;
		}
	}
}

The problem is that it removes everything after the first space is found. Anyone know what I'm doing wrong?

[m4ster r0shi]

Try doing it using two strings. The original and one to store the result. Read the original and write to the result only if there are no consecutive spaces.

EDIT: There's a smarter way, using istringstream ;)

( http://cplusplus.com/reference/iostream/istringstream/ )

[RedX]

for( int i  = 0; i < in->length(); ++i){
  if(isspace(in[i])){
    in->erase(i,1);
  }
}

[m4ster r0shi]

@RedX: I tried what you suggested and it doesn't seem to work :/

Anyway, the istringstream way is this:

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

string SpaceTrim(const string & s);

int main()
{
    string input;

    cout << "enter input string:\n\n";
    getline(cin,input,'\n');

    cout <<  SpaceTrim(input) << endl;

    cout << "hit enter to quit..." << endl;
    cin.get();

    return 0;
}

string SpaceTrim(const string & s)
{
    istringstream iss(s);
    string result;
    string temp;

    //take advantage of the fact that
    //istream::operator>> skips whitespaces ;)
    while (iss>>temp)
    {
        result+=temp;
        
        //add exactly one whitespace
        //after each word
        result+=' ';
    }

    //remove last whitespace
    result.erase(result.end()-1);

    return result;
}

[RedX]

This one works

for( int i  = 0; i < in->length(); ++i){
  if(isspace(in->at(i))){
    *in = in->erase(i,1);
  }
}

[R0mai]

@RedX
It does, but it doesn't do what OP wants. He only wants to remove unnecessary whitespaces.
E.g.: " hello world! " -> "hello world!"

[fafner]

Awesome, the istringstream works;) I'm just curious, because I used another implementation of the code in the original post, bit without the input being a pointer. It looks like this, and works fine:

string parseInput(string in, Bot *b) {
	char prevChar = ' ';
	for(int i = 0; i < in.length(); i++) {
		if (in[i] >= 'a' && in[i] <= 'z')
			in[i] -= ('a' - 'A');
		
		if (in[i] == '?')
			b->setQuestion(true);
			
		if (in[i] == ' ' && prevChar == ' ' || isPunc(in[i])) {
			in.erase(i, 1);
			i--;
		}
		
		prevChar = in[i];
	}
	return in;
}

I'm just wondering why this works, and not the other?

Thanks, all!