小编Fla*_*res的帖子

嘿,我喜欢尽可能快地制作它,因为它在我正在编写的程序中被称为A LOT,所以有没有更快的方法将C++向量初始化为随机值:

double range;//set to the range of a particular function i want to evaluate.
std::vector<double> x(30, 0.0);
for (int i=0;i<x.size();i++) {
    x.at(i) = (rand()/(double)RAND_MAX)*range;
}

编辑:修复了x的初始化程序.

嘿,我想知道如何让这段代码工作.基本上我想保留行,$filename只要它们包含$user在路径中:

        open STDERR, ">/dev/null";
        $filename=`find -H /home | grep $file`;
        @filenames = split(/\n/, $filename);
        for $i (@filenames) {
            if ($i =~ m/$user/) {
                #keep results
            } else {
                delete  $i; # does not work.    
            }
        }
        $filename = join ("\n", @filenames);
        close STDERR;

我知道你可以删除,delete $array[index]但我没有这种循环的索引,我知道.