post  argument passing

CD4 (28)   Link to this post
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#include<unistd.h>
#include<stdio.h>

int main(int argc,char *argv[]) {
int opt=0;
extern int optind,opterr,optop;
  while (opt=getopt(argc,argv,":hw:ra")!=-1) {
    switch (opt) {
      case 'h': //{
        printf("HELP IS HERE\n");
        break;
      //}
      case 'r':
      case 'a': 
        printf("OPTION: %c\n",opt);
        break;
      case 'w':
        printf("The option has an argument: %s\n","optarg");
        break;
      case ':':
        printf("%s\n","ERROR:ENTER VALUE FOR OPTION");
        break;
    }
  }
return 0;
}

Hello... is there anything wrong with the code.When i give ./(programname) -h
there is no output..
regards
Seph (2)   Link to this post
Hello !!

The problem is the line 7 => while (opt=getopt(argc,argv,":hw:ra")!=-1)

The = ( atribution operator ) have a lower precedence than the != ( diferent operator ), in other words, your code on this line, is avaliable in this form => while ( opt = ( getopt(argc,argv,":hw:ra") ) != -1 ).

As you see, the getopt function are compared with the "-1" before the opt variable get the value.


To fix the problem, just put the parentheses on the right place.

while ( ( opt = getopt(argc, argv, ":hw:ra") ) != - 1 )

I make a test here, using the parentheses of this form and the program run without any problems.
CD4 (28)   Link to this post
ok.. die to this the problem was occouring.. thanks for helping me :-)

regards

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