C using getOpt to parse multiple arguments - c

Question

I need to use getopt to parse the following command:
./center -n name –cp Anumber –i Anumber –t Anumber –s Anumber -fc nameOfaFile
All of them can be given out in any order.
So its clear i have to use getOpt.
So i have been investigation and this is what i have so far
void check_parameters (int argc, char** argv) {
int opt;
while((opt = getopt(argc, argv, "n:cp:i:c:fc:")) != -1) {
printf("give me opt %c \n", opt)
swicth(opt){
case 'n' :
//do something
case 'cp' :
//do something
case 'i' :
//do something
}
}
}
I do know for a fact that the 3 parameter: the OptString is where i tell getOpt what are the char of the options it should expect
Also in optarg is where the argument is
its not working!
when i printf( "give me opt %c", opt ) its giving me the numbers, not the char!
for this reason it does not work. it does not check the parameters correctly
Edit:
After doing man 3 getopt
the return value of getopt is: If an option was successfully found, then getopt() returns the option character. If all command-line options have been parsed, then getopt() returns -1.
it returns the option character? it always return integer 1. always! i don't understand how getopt works. how does the switch compare to characters?!

Answer 1

First of all, this:
case 'cp':
...makes no sense. You can't represent two characters with a char or int. Besides, if running your program with -cp 101, getopt will treat it as -c p 101, for a completely different result. If you want to use long options, use getopt_long instead and the appropriate calling syntax, per example: ./a.out -n 42 --cp 101.
Now, here's a working example of getopt() in action:
#include <stdio.h>
#include <getopt.h>
int main(int argc, char* argv[]) {
int opt;
while((opt = getopt(argc, argv, "n:cp:i:c:fc:")) != -1) {
switch (opt){
case 'n':
printf("n was %s\n", optarg);
break;
case 'i':
printf("i was %s\n", optarg);
break;
}
}
return 0;
}

Answer 2

getopt handles only single-character option names, not things like -cp or -fc (which it interprets as multiple option flags in a single string: -c -p, -f -c). If you want to stick to the syntax you defined, then it's easier to just roll your own:
// first check whether argc is odd, then:
for (i = 1; i < argc; i += 2) {
if (strcmp(argv[i], "n") == 0) {
name = argv[i+1];
} else if (strcmp(argv[i], "cp") == 0) {
// etc. etc.
}
}