#include

using std::cout, std::cin, std::cerr, std:: endl;

#include

using std::string;

#include

using std::istringstream, std::istream, std::ifstream;

void printError$($const char$*$ fileName$)\{$

cerr $<<$ "ERROR: can't open" $<<$ fileName $<<$ endl;

$\}$

$//$istream general input

void head $($istream& input, int numLines$)\{$

string line;

int linesRead $=0$;

while $($linesRead $<$ numLines && getline$($input$,$ line$))\{$

linesRead$++$;

cout $<<$ line $<<$ endl;

$\}$

$\}$

int main $($int argc, char$*$ argv$[])\{$

int numLines $=10$;

$//$if no arguments provided, read $10$ lines

if $($argc $==1)\{$

head$($cin$,$ numLines$)$;

$\}$

else if $($argc $==2)\{$

$//$if two arguments are provided, read the specified number of lines

$//$check it's a number or a filename

ifstream file$($argv$[1])$;

if $($file$.$is$\_$open$())\{$

head$($file$,$ numLines$)$;

$\}$

else $\{$

printError$($argv$[1])$;

return $1$;

$\}$

$\}$

ifstream file$($argv$[1])$;

if $($file$.$is$\_$open$())\{$

head$($file$,$ numLines$)$;

$\}$

else $\{$

$//$file that does not exist example

printError$($argv$[0])$;

return $1$;

$\}$

return $0$;

$\}$

how would i modify my code to meet these requirements?

Write a head program in head.cpp

$.$

The head program should read the first n lines of either a file or standard input

If n isn't provided, print

$1$

$0$

$$lines

If no file is provided, read the lines from standard input

$($

cin

$)$

There are four possible scenarios for command

$-$

line arguments:

No arguments: the program should read

$1$

$0$

$$lines from standard input.

$1$

$$argument that is an input file: the program should attempt to read

$1$

$0$

$$lines from the file.

$1$

$$argument that is a number of lines n: the program should read that number of lines from standard input.

$-$

NOTE: Empty lines

$($

$"$

$"$

$)$

$$count as valid input. The program should accept them the same way it accepts non

$-$

empty lines.

$2$

$$arguments: the program should read n lines from the file.

If the input file does not exist, the program should print an error message and exit

If more lines are requested than the input file has, the program should just print as many lines as the file has and no extras.

Follow the formatting demonstrated in the example