Programm in Freedos and djgpp chashes when using commandline paramters

Hallo guys!

I have tried just for fun to work with FreeDOS 1.2 and djgpp to write some
programs in c.
But when i try to access arguments argv[] from (example)

Code:

---

int main(it argc, char *argv[]){
.......

result = strcmp(argv[1], "/?");

---

to try

Code:

---

int main(it argc, char **argv){

---

has the same results.

the source will compile and link without errors, but if i call the exe the
Programm will crash with SIGSEGV as an error.
By other compilers the same code works fine.

Where lies the rabbit in the pepper?

I hope "it argc" is a typo, it should be "int argc".

How exactly are you calling the program?

What are your actual command line arguments?

Quote:

---

Originally Posted by rusyoldguy

Hallo guys!

I have tried just for fun to work with FreeDOS 1.2 and djgpp to write some
programs in c.
But when i try to access arguments argv[] from (example)

Code:

---

int main(it argc, char *argv[]){
.......

result = strcmp(argv[1], "/?");

---

to try

Code:

---

int main(it argc, char **argv){

---

has the same results.

the source will compile and link without errors, but if i call the exe the
Programm will crash with SIGSEGV as an error.
By other compilers the same code works fine.

Where lies the rabbit in the pepper?

---

If the program is called with no arguments to the program, then accessing argv[1] or higher would be illegal.

Us the following to display the command line arguments:

Code:

---

#include <stdio.h>

int main(int argc, char *argv[])
{
  int x = 0;

  printf("argc == %d\n", argc);

  for(x = 0; x < argc; x++)
  {
      printf("argv[%d] == %s\n", x, argv[x]);
  }

  return 0;
}

---

Run this with no command line args, and with various number of args to see the results.

sorry, my fault.#

In the original code i used

int argc

What i don't understand is, when i call the programm without any argument it crashes in FreeDOS.
The same EXE works fine if i call it with a given argument, like "/?" "help" or anything.
I wrote it 1995 with qc25 compiler of MSDOS.

The original MSDOS had no Program to rename a directory:

Code:

---

/* Programm rendir.c benennt Verzeichnisse um */
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>

void Autor(void)
{
 printf("Test-Version\n");
/* Name of Author */


}


int main(int argc, char *argv[])
{
 int frage;
 char altername[300], neuername[300];

if(((strcmp(argv[1], "/?")) == 0) || ((strcmp(argv[1], "/h")) == 0) || \
        ((strcmp(argv[1], "help")) == 0))
      {
        AUTOR();
        printf("\nRENDIR.EXE .... Ein Programm zum Umbenennen von Verzeichnissen");
        printf("\ngeschrieben fuer MS-DOS Betriebssysteme");
        printf("\nSyntax: rendir alter_Verzeichnissname neuer_Verzeichnissname");
        getch();
        return(0);
      }
 if(argc != 3)
  goto keinargument;
 
 strcpy(altername, argv[1]);
 strcpy(neuername, argv[2]);
 goto request;

 keinargument: printf("\nRENDIR.EXE .... Ein Programm zum Umbenennen von Verzeichnissen");
              printf("\ngeschrieben fuer MS-DOS Betriebssysteme");
              printf("\nSyntax: rendir alter_Verzeichnissname neuer_Verzeichnissname");
              printf("\nEnde........e oder E");
              printf("\nInfo........i oder I");
              printf("\nWeiter......beliebige Tate");
 
        frage = getche();
        if ((frage == 'e') || (frage == 'E'))
        return(0);
        if ((frage == 'i') || (frage == 'I'))
        {
        AUTOR();
        return(0);
        }
       
        printf("\nAlter Verzeichniss-Name: ");
        scanf("%s", altername);
        printf("\nNeuer Verzeichniss-Name: ");
        scanf("%s", neuername);
 request:
 printf("\nAlter Name:%s\nNeuerName :%s\n", altername, neuername);
 printf("\nWollen Sie wirklich diese Verzeichniss umbenennen(j/n)");

 frage = getche();
 if ((frage == 'n') || (frage == 'N'))
  return(0);

 frage = rename( altername, neuername );
 if (frage != 0)
  {
  printf("\nUmbenennung fehlgeschlagen\n");
  printf("\nBitte geben Sie beim alten und beim");
  printf("\nneuen Verzeichnissnamen den kompletten Pfad an\n");
  }
 

return(0);
}

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I work with an emulator qemu-kvm on SUSE Linux tumbleweed. At the same emulated Freedos i have an old
QC25 compiler, with it i have no Problems. Why does progams where compiled for DOS with DJGPP don't like
a call without arguments?Attachment 16081

Same results i've got with compile and link with RHIDE.EXE.
Also i compiled and linked on with gcc himself. No other results.

The code is incorrect, that's why. You need to ensure that the index is less than `argc`. Period.

Here a call with given argument:
Attachment 16082Attachment 16082

See my previous response!

If the program is called with NO COMMAND LINE ARGUMENTS, then attempting to access argv[1], argc[2], argc[3], ... is ILLEGAL!!! You can ONLY access argv[0] through argv[argc - 1]!

You should check argc first. If you program requires command line arguments, then print an error message, and end the program if argc is too low!

I would also recommend losing all the gotos and create functions.

Thank You!

Now it works!

I think i had Tomatoes on the eyes!
He who makes no mistakes makes nothing.