How to improve left trim function?

**jim_0** · 07-23-2014

This works, if just loops through till it doesn't find a space or tab than counts the index at that point then uses substr to get rid of any spaces/tabs, it's a small function and uses a goto I am just wondering how you would do it?

Code:

string trimLeft(string lineOfCodeToTrim){
    string l = lineOfCodeToTrim;
    int k =0;
    
    for(UINT i = 0;i<l.length();i++){
        //FIXME: Just need l[i] != ' ' && l[i] != '\t";
        if(((int)l[i] < 32 || (int)l[i] > 32) && ((int)l[i] != 9)){
            goto l1;
            }
        k++;
        }
l1:
    if(k > 0){
        l = l.substr(k ,lineOfCodeToTrim.length() - k);
        }
    return l;
    }

**Codeplug** · 07-23-2014

Code:

#include <iostream>
#include <string>

using namespace std;

void LeftTrim(string &s)
{
    const char ToTrim[] = " \t";
    s.erase(0, s.find_first_not_of(ToTrim));
}//LeftTrim

int main()
{
    string s = "\t   Hello\tWorld\t ";
    LeftTrim(s);
    cout << "[" << s << "]"<< endl;
    return 0;
}//main

gg

**grumpy** · 07-23-2014

Originally Posted by jim_0

Code:

        if(((int)l[i] < 32 || (int)l[i] > 32) && ((int)l[i] != 9))

Blech! Magic values (like 32 and 9) are not a good idea, since different character sets use different values for things like spaces and tabs.

The expression "a < b || a > b" is more easily expressed as "a != b" too.

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