how to not display the user input password

Question

hi friends, how to not display the user input password in C,It is similar to the oracle SQL Plus .This is also for safety reasons. thanks.

Vulpes · Answer

On my Windows keyboard, pressing those keys (and all the other non-printing characters such as Insert, Delete. Pgup, PgDn etc) generates two characters of which the first one is either 0x00 or 0xE0. So to stop them printing an asterisk, we need to trap these two characters and the next character as well. I've altered the program to deal with that but, if you're using an OS other than Windows or a non-English keyboard, then I can't promise it will work as the keyboard mappings may be different. I've also replaced the isalnum() library function with the corresponding bool expression as the former seems to have some issues when passed non-printing characters: #include "stdio.h" #include "conio.h" #include "ctype.h" int main() { char password[15]; /* max length 14 characters say */ int i; for(i = 0; i int index = 0; int controlKey = 0; printf("Enter password : "); while(index { char ch = getch(); if (controlKey == 1) { controlKey = 0; } else if(ch == 13) /* enter key */ { break; } else if (ch == 8) /* backspace key */ { if (index > 0) { putchar(8); putchar('\0'); putchar(8); index--; password[index] = '\0'; } } else if ((ch >= 'a' && ch = 'A' && ch = '0' && ch { putchar('*'); password[index] = ch; index++; } else if (ch == 0 || ch == -32 ) { controlKey = 1; } } printf("
Your password is %s

", password); return 0; }

Ken H · Answer

if enter up,down,left,right key,it will show the two star,why? how to Prohibit non-numeric and alphanumeric characters. thanks

Ken H · Answer

thank for Vulpes

Vulpes · Answer

I've no idea how Oracle SQL Plus deals with passwords but the following C program will hide the password entered (up to 14 alphanumeric characters) by displaying asterisks instead. It also supports the backspace key and (of course) the enter key: #include "stdio.h" #include "conio.h" #include "ctype.h" int main() { char password[15]; /* max length 14 characters say */ int index = 0; int i; for(i = 0; i printf("Enter password : "); while(index { char ch = getch(); if(ch == 13) /* enter key */ { break; } else if (ch == 8) /* backspace key */ { if (index > 0) { putchar(8); putchar('\0'); putchar(8); index--; password[index] = '\0'; } } else if (isalnum(ch)) { putchar('*'); password[index] = ch; index++; } } printf("
Your password is %s

", password); /* Check it worked */ return 0; }

Ken H · Answer

hi Atul Kumar , I want to achieve the same effect with the oracle SQL Plus,is DOS-based. thanks

Atul Kumar · Answer

You can use the font-color of password same as the background of the textbox.

how to not display the user input password

Answers (6)