Programming Forums > Application Development > C

Navid · Jun 28th, 2005, 5:53 PM

This is a program where you input a password, and for each char it prints a *.
But when the user presses backspace, it erases the unechoed char that was inputed, but not the *.

(Toggle Plain Text)

#include <stdio.h>

char pass[10];
int count=0;

int main(void)
{
printf("Enter new password (10 characters max):");

while ( (pass[count++]=getch()) != '\r')
{

if(count > 10)
{
for (count=0; count<10; count++)
{
pass[count] = '\0';
}
printf("\n\nYour password is too long, enter it again:");
count = 0;
continue;
}
else
{
if (pass[count-1] == '\b' && count==1)
{
count=0;
continue;
}
else
{
if (pass[count-1] == '\b')
{
printf("\b");
count -= 2;
}
else
{
printf("*");
}
}
}

}
puts("\n\nYour new password is:");puts(pass);
printf("\n");
system("pause");
return 0;
}

So what should I do so it erases the * when the user presses backspace?

noliviawalton · Jun 28th, 2005, 6:09 PM

What software have you been doing this programmer in? Also why do you have so many braces in the program?

Navid · Jun 28th, 2005, 6:16 PM

Well thanks for registering just to anwser me

I'm using Dev-C++, the braces are for the ifs. A switch is usally a better way of using ifs but, meh

Ooble · Jun 28th, 2005, 6:27 PM

Print this: "\b \b". That'll move the cursor back one, print a space (thereby erasing whatever's there), and move it back again.

jim mcnamara · Jun 28th, 2005, 6:31 PM

if this is a unix box try:

(Toggle Plain Text)

#include <unistd.h>
int main()
{
     char *pass=NULL;
     pass=getpass("Enter password");
     return 0;
}

Navid · Jun 28th, 2005, 6:38 PM

printing "\b" only erases the char gotten by getch (the unechoed char).

DaWei · Jun 28th, 2005, 7:05 PM

Do as Ooble suggests. Printing \b moves the cursor back to the previous character on the screen. Printing space overwrites it. Printing \b again repositions you to that character on the screen. You'll also need to discard the character you read when you see the backspace from the keyboard.

Navid · Jun 28th, 2005, 9:17 PM

ahh
got it, just wasn't printing the space to erase it. Thanks.
Solved.

InfoGeek · Jun 28th, 2005, 11:07 PM

Quote:

Originally Posted by navnav

(Toggle Plain Text)

if(count > 10)
{
   ..
   ..

i think it should be

(Toggle Plain Text)

if(count>7)
{
  ..
  ..

DaWei · Jun 29th, 2005, 8:19 AM

Why 7?

He says in the prompt that the password is 10 characters, maximum.

Jun 28th, 2005, 5:53 PM	#1
Navid Hobbyist Programmer Join Date: Feb 2005 Location: Canada Posts: 187 Rep Power: 4	Password Program This is a program where you input a password, and for each char it prints a . But when the user presses backspace, it erases the unechoed char that was inputed, but not the . (Toggle Plain Text) #include <stdio.h> char pass[10]; int count=0; int main(void) { printf("Enter new password (10 characters max):"); while ( (pass[count++]=getch()) != '\r') { if(count > 10) { for (count=0; count<10; count++) { pass[count] = '\0'; } printf("\n\nYour password is too long, enter it again:"); count = 0; continue; } else { if (pass[count-1] == '\b' && count==1) { count=0; continue; } else { if (pass[count-1] == '\b') { printf("\b"); count -= 2; } else { printf(""); } } } } puts("\n\nYour new password is:");puts(pass); printf("\n"); system("pause"); return 0; } #include <stdio.h> char pass[10]; int count=0; int main(void) { printf("Enter new password (10 characters max):"); while ( (pass[count++]=getch()) != '\r') { if(count > 10) { for (count=0; count<10; count++) { pass[count] = '\0'; } printf("\n\nYour password is too long, enter it again:"); count = 0; continue; } else { if (pass[count-1] == '\b' && count==1) { count=0; continue; } else { if (pass[count-1] == '\b') { printf("\b"); count -= 2; } else { printf(""); } } } } puts("\n\nYour new password is:");puts(pass); printf("\n"); system("pause"); return 0; } So what should I do so it erases the * when the user presses backspace?

Jun 28th, 2005, 6:27 PM	#4
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	Print this: "\b \b". That'll move the cursor back one, print a space (thereby erasing whatever's there), and move it back again. __________________ Me :: You :: Them

Jun 28th, 2005, 6:31 PM	#5
jim mcnamara Hobbyist Programmer Join Date: Jun 2005 Location: New Mexico Posts: 228 Rep Power: 4	if this is a unix box try: (Toggle Plain Text) #include <unistd.h> int main() { char pass=NULL; pass=getpass("Enter password"); return 0; } #include <unistd.h> int main() { char pass=NULL; pass=getpass("Enter password"); return 0; }

Jun 28th, 2005, 7:05 PM	#7
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Do as Ooble suggests. Printing \b moves the cursor back to the previous character on the screen. Printing space overwrites it. Printing \b again repositions you to that character on the screen. You'll also need to discard the character you read when you see the backspace from the keyboard. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jun 29th, 2005, 8:19 AM	#10
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Why 7? He says in the prompt that the password is 10 characters, maximum. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jun 28th, 2005, 6:09 PM	#2
noliviawalton Newbie Join Date: Jun 2005 Location: Washington,DC Posts: 8 Rep Power: 0	What software have you been doing this programmer in? Also why do you have so many braces in the program?

Jun 28th, 2005, 6:16 PM	#3
Navid Hobbyist Programmer Join Date: Feb 2005 Location: Canada Posts: 187 Rep Power: 4	Well thanks for registering just to anwser me I'm using Dev-C++, the braces are for the ifs. A switch is usally a better way of using ifs but, meh

Jun 28th, 2005, 6:38 PM	#6
Navid Hobbyist Programmer Join Date: Feb 2005 Location: Canada Posts: 187 Rep Power: 4	printing "\b" only erases the char gotten by getch (the unechoed char).

Jun 28th, 2005, 9:17 PM	#8
Navid Hobbyist Programmer Join Date: Feb 2005 Location: Canada Posts: 187 Rep Power: 4	ahh got it, just wasn't printing the space to erase it. Thanks. Solved.

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Programming Forums > Application Development > C

Password Program