Sample program to work with CLI options. Play with this program options and pay attention to the reported usage errors to better understand how GetOptions() work. # CODE STARTS HERE
#!perl -w =head1 Using GetOptions() to process CLI options Ref: http://perldoc.perl.org/Getopt/Long.html =cut # Required module use Getopt::Long; use strict; my $grade = 'A'; my $pcile = 0.0; my $name = ''; my $result = 0; # Fail by default my $promote = 0; my @marks = (); my %history = (); sub show_usage() { print "\nUsage: --name name --grade [A|B|C|D] --marks m1 m2 m3\n" . " [--pass] [--promote | --nopromote]\n\n"; exit( 0 ); } if ( !scalar( @ARGV ) ) { show_usage(); } if ( !GetOptions( 'name=s' => \$name, # = - mandatory, string 'grade:s' => \$grade, # : - optional, string 'percentile:f' => \$pcile, # read float value 'marks=i{3}' => \@marks, # sequence of 3 numerals 'pass' => \$result, # optional, flag 'promote!' => \$promote, # -promote and -nopromote 'history:s{2}' => \%history ) ) # sequence of 2 strings { show_usage(); } print "\n SUMMARY \n\n"; print "Name : $name\n"; print "Marks : "; foreach( @marks ) { print $_ . " "; } print "\n"; print "Grade : $grade\n"; print "Percentile: $pcile\n"; print "Result : $result\n"; print "Promote? : $promote\n"; print "\n"; print "History : "; foreach( keys( %history ) ) { print $_ . " = " . $history{$_} . "; "; } print "\n"; 0; # CODE ENDS HERE
int process_data( const char * str, char delim = ' ' );Suddenly another component that depends on the modified header fails to compile with error C2143: missing ')' before 'string'. That's a bit of shock!. By the way the other component doesn't use the new API at all.
#define delim TEXT(" ") // andYou are punished for using a simple looking identifier (delim) and it takes efforts to understand that you are being punished!
#define TEXT( str ) L##str // just token pasting ...
#define INT32_MIN -2147483648
if ( 1 > INT32_MIN ) // comparing two unsigned values
std::cout << "I am sure, 1 gt INT32_MIN";
else
std::cout << "Surprse! it says, 1 lt INT32_MIN";
#define INT32_MIN (-2147483647 - 1) // don't forget to put the braces around
void PrintUsage()
{
std::cout << "#mycmd -option1 -subopt1 -subopt2 -suboption3 \n\
-option2 -subopt1 -sbuopt2 -subopt3 \n\
......................... \n\
......................... \n\
-option15 -subopt1 -subopt2"
<< std::endl;
}
void PrintUsage()
{
std::cout << "#mycmd -option1 -subopt1 -subopt2 -suboption3 \n\
-option2 -subopt1 -sbuopt2 -subopt3 \n\
......................... \n\
.........................\n\
-option9 -subopt1 -subopt2";
std::cout << " -option10 -subopt1 -subopt2 -suboption3 \n\
-option11 -subopt1 -sbuopt2 -subopt3 \n\
......................... \n\
.........................\n\
-option15 -subopt1 -subopt2";
<< std::endl;
}
