string tips

This is a discussion on string tips within the C++ Programming forums, part of the General Programming Boards category; Anyone got a good way to do this without having to use a c-string (and <cstring>): Code: #include <iostream> #include ...

  1. #1
    spurious conceit MK27's Avatar
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    string tips

    Anyone got a good way to do this without having to use a c-string (and <cstring>):
    Code:
    #include <iostream>
    #include <string>
    #include <cstring>
    using namespace std;
    
    void stripWS(string &str) {
    	int len = str.size();
    	char copy[len+1], *p;
    	strcpy(copy,str.c_str());
    	p = &copy[len-1];
    	while (*p == ' ' || *p == '\t') *(p--) = '\0';
    	p = copy;
    	while (*p == ' ' || *p == '\t') *p++;
    	str = p;
    }
    
    
    int main() {
    	string test("\t\t so what\t   ");
    
    	cout << "->" << test << "<-\n";
    	stripWS(test);
    	cout << "->" << test << "<-\n";
    
    	return 0;
    }
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  2. #2
    C++ Witch laserlight's Avatar
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    I have not tested it, but perhaps something like this will work:
    Code:
    void stripWS(string& str) {
        const string::size_type first = str.find_first_not_of(" \t");
        if (first != string::npos)
        {
            const string::size_type last = str.find_last_not_of(" \t");
            str = str.substr(first, last - first + 1);
        }
        else
        {
            str.clear(); // The string only comprises of whitespace.
        }
    }
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
    spurious conceit MK27's Avatar
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    Yeah, that's the kind of thing I was thinking of. Seems to work too. Thanks!
    Last edited by MK27; 03-22-2010 at 10:25 AM.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

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