I know there are several ways to do this in Java and C that are nice, but in C++ I can't seem to find a way to easily implement a string trimming function.
This is what I currently have:
string trim(string& str)
{
size_t first = str.find_first_not_of(' ');
size_t last = str.find_last_not_of(' ');
return str.substr(first, (last-first+1));
}
but whenever I try and call
trim(myString);
I get the compiler error
/tmp/ccZZKSEq.o: In function `song::Read(std::basic_ifstream<char,
std::char_traits<char> >&, std::basic_ifstream<char, std::char_traits<char> >&, char const*, char const*)':
song.cpp:(.text+0x31c): undefined reference to `song::trim(std::string&)'
collect2: error: ld returned 1 exit status
I am trying to find a simple and standard way of trimming leading and trailing whitespace from a string without it taking up 100 lines of code, and I tried using regex, but could not get that to work as well.
I also cannot use Boost.
Your code is fine. What you are seeing is a linker issue.
If you put your code in a single file like this:
#include <iostream>
#include <string>
using namespace std;
string trim(const string& str)
{
size_t first = str.find_first_not_of(' ');
if (string::npos == first)
{
return str;
}
size_t last = str.find_last_not_of(' ');
return str.substr(first, (last - first + 1));
}
int main() {
string s = "abc ";
cout << trim(s);
}
then do g++ test.cc
and run a.out, you will see it works.
You should check if the file that contains the trim
function is included in the link stage of your compilation process.