getopt_long is useful to work with the command line arguments. But while working with getopt_long, — is used for long options and – for short options. getopt_long_only accepts both — and – for long options
- rectangle -a -l 12 -b 34: will calculate the area of the rectangle
- square -p -l 12 -b 34: will calculate the perimeter of the rectangle
- rectangle -a -p -l 12 -b 34: will calculate the area and perimeter of the rectangle
- rectangle –area –length 12 –breadth 34: will calculate the area of the rectangle
- square -perimeter –length 12 –breadth 34: will calculate the perimeter of the rectangle
- rectangle -area -perimeter –length 12 –breadth 34: will calculate the area and perimeter of the rectangle
The program is much like getopt_long.
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
/** Program to calculate the area and perimeter of
* a rectangle using command line arguments
*/
void print_usage() {
printf("Usage: rectangle [ap] -l num -b num\n");
}
int main(int argc, char *argv[]) {
int opt= 0;
int area = -1, perimeter = -1, breadth = -1, length =-1;
//Specifying the expected options
//The two options l and b expect numbers as argument
static struct option long_options[] = {
{"area", no_argument, 0, 'a' },
{"perimeter", no_argument, 0, 'p' },
{"length", required_argument, 0, 'l' },
{"breadth", required_argument, 0, 'b' },
{0, 0, 0, 0 }
};
int long_index =0;
while ((opt = getopt_long_only(argc, argv,"",
long_options, &long_index )) != -1) {
switch (opt) {
case 'a' : area = 0;
break;
case 'p' : perimeter = 0;
break;
case 'l' : length = atoi(optarg);
break;
case 'b' : breadth = atoi(optarg);
break;
default: print_usage();
exit(EXIT_FAILURE);
}
}
if (length == -1 || breadth ==-1) {
print_usage();
exit(EXIT_FAILURE);
}
// Calculate the area
if (area == 0) {
area = length * breadth;
printf("Area: %d\n",area);
}
// Calculate the perimeter
if (perimeter == 0) {
perimeter = 2 * (length + breadth);
printf("Perimeter: %d\n",perimeter);
}
return 0;
}
Programming in Linux 