About ' * ' not recognized

About ' * ' not recognized

[naoki ueda]

[-- Attachment #1: Type: text/plain, Size: 323 bytes --]

When I tried to execute the attached file mycalc.c with a command line
argument, it could not be executed normally only in the case of '*'.
'+', '-' and '/' can be executed normally, but the compiler cannot
execute '*' normally. Isn't this a gcc bug?


~/Clearning$ ./mycalc 20 * 30
用法:mycalc 数値1 演算子 数値2

[-- Attachment #2: mycalc.c --]
[-- Type: text/x-csrc, Size: 929 bytes --]

#include <stdio.h>
#include <stdlib.h>             // for exit()
#include <string.h>             // for strcpy() strlen()
int main(int argc, char *argv[])
{
     double d1, d2,ans;
     char ope[80];
     
     if (argc != 4) {
          printf("用法:mycalc 数値1 演算子 数値2\n");
          exit(1);
     }
     d1 = atof(argv[1]);
     d2 = atof(argv[3]);
     strcpy(ope,argv[2]);
     if (strlen(ope) != 1) {
          printf("演算子が1文字でない\n");
          exit(1);
     }
     switch (ope[0]) {
     case '+':
          ans = d1 + d2;
          break;
     case '-':
          ans = d1 - d2;
          break;
     case '*':
          ans = d1 * d2;
          break;
     case '/':
          if (d2 == 0.0) ans = 0.0;    // 0除算対応
          else ans = d1 / d2;
          break;
     default:
          printf("演算子が違っている\n");
          exit(1);
     }
     printf("%f\n",ans);
}

Re: About ' * ' not recognized

[Andrew Pinski]

On Fri, Jan 20, 2023 at 5:05 PM naoki ueda via Gcc-bugs
<gcc-bugs@gcc.gnu.org> wrote:
>
> When I tried to execute the attached file mycalc.c with a command line
> argument, it could not be executed normally only in the case of '*'.
> '+', '-' and '/' can be executed normally, but the compiler cannot
> execute '*' normally. Isn't this a gcc bug?

First off this email list is really for automated messages from gcc's
bugzilla rather than from users reporting issues.

>
>
> ~/Clearning$ ./mycalc 20 * 30

Oh * here is being handled by the shell you are using and being
expanded as all the files in the current working directory. This has
nothing to do with GCC really.
You can use quotes around the * to force the shell not expanding it
such as this:
./mycalc 20 '*' 30

or you use \ to force the shell not to expand what comes after the * like this:
./mycalc 20 \* 30

Thanks,
Andrew Pinski

> 用法:mycalc 数値1 演算子 数値2

Re: About ' * ' not recognized

[naoki ueda]

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Ok, I see.

2023年1月21日(土) 10:12 Andrew Pinski <pinskia@gmail.com>:

> On Fri, Jan 20, 2023 at 5:05 PM naoki ueda via Gcc-bugs
> <gcc-bugs@gcc.gnu.org> wrote:
> >
> > When I tried to execute the attached file mycalc.c with a command line
> > argument, it could not be executed normally only in the case of '*'.
> > '+', '-' and '/' can be executed normally, but the compiler cannot
> > execute '*' normally. Isn't this a gcc bug?
>
> First off this email list is really for automated messages from gcc's
> bugzilla rather than from users reporting issues.
>
> >
> >
> > ~/Clearning$ ./mycalc 20 * 30
>
> Oh * here is being handled by the shell you are using and being
> expanded as all the files in the current working directory. This has
> nothing to do with GCC really.
> You can use quotes around the * to force the shell not expanding it
> such as this:
> ./mycalc 20 '*' 30
>
> or you use \ to force the shell not to expand what comes after the * like
> this:
> ./mycalc 20 \* 30
>
> Thanks,
> Andrew Pinski
>
> > 用法:mycalc 数値1 演算子 数値2
>