Question

I have a text file with a lot of lines, and in each line, there are several columns divided by space character, but the number of columns in each line varies. For example, here is a sample

——————–
abc 123 234 456
bsc 3 5 7 9 10 123
yyt 23
——————–

I want to get a new file based on the existing file, by removing the first column, here is the related output of above sample,

--------------------
123 234 456
3 5 7 9 10 123
23
--------------------

Solution

perl is a bit faster than cut:

perl -pe ‘s/^[^ ]+\ *//’

Sed is a slower:

sed -e ‘s/^[^ ]\+\ *//’

Note: If you accept leading space characters, cut won’t work properly (it would treat the first field as being empty), but perl can work:

perl -pe ‘s/^\ *[^ ]+\ *//’

a little more robust program.

#include
#include

int main(int argc, char* argv[])
{
using std::string;

while (1)
{
string str_one_line;
if (!getline(std::cin, str_one_line))
break;

string::size_type pos = str_one_line.find_first_of(‘ ‘);
if (pos == string::npos)
{
std::cerr << "There is no space char in the string." << std::endl;
return 1;
}

pos = str_one_line.find_first_not_of(' ', pos + 1);
if (pos == string::npos)
{
std::cerr << "There is no char after space char." << std::endl;
return 1;
}

std::cout << str_one_line.substr(pos) << std::endl;
}
return 0;
}

Tags: File, How-to, Script