[SOLVED] Problem with scanf--->SemiBeginner

[hakermania]

Hi, I'm quite a beginner in C++.I am working in QtCreator.I have made a program which co-operates with some .sh executable files. I have a problem when the scanf command takes a character and not a number.Well, to make you understand better, this is my program:

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int a;
    while (1){
    printf("If you are not root, please become...\n\n 1 = What's my mac?               7 = Start aircrack-ng and hack them all\n 2 = Change my mac                8 = Send DeAth to broadcast\n 3 = Start capturing IVS          9 = See available modems\n 4 = Start Reading files         10 = What's my interface? \n 5 = Stop interface              11 = About this prog \n 6 = Start interface             12 = Exit \n");
    scanf("%d",&a);
    if (a==1) system("/etc/macchanger1.sh");
    else if (a==2) system("/etc/macchanger2.sh");
    else if (a==3) system("/etc/dumpcapt.sh");
    else if (a==4) system("/etc/aireplayread.sh");
    else if (a==5) system("/etc/airmonstop.sh");
    else if (a==6) system("/etc/airmonstart.sh");
    else if (a==7) system("/etc/aircrack.sh");
    else if (a==8) system("/etc/aireplaysenddeath.sh");
    else if (a==9) system("/etc/airodump-ng.sh");
    else if (a==10) system("/etc/airmon-ng.sh");
    else if (a==11) printf(" This prog was written on February 2010 with purpose to make your life easier\n in hacking yours WEP modems...Cheers!!!\n Note that you must have installed macchanger and aircrack-ng \n");
    else if (a==12) break;
    else if (a<=1 || a>=12) printf("Please type a number from 1 to 12\n");
    else {printf("ERROR\n"); break;}
    }
        return 0;

}

Well, as you can see the program when being run, shows a menu which allows you to choose what you want to do.The problem is that when somebody gives a character (for example "a" or "b" or "school" or anything else) and no a number the program goes mad and starts the menu again and again till I push Ctrl+C
I have put the last "else" in order to avoid this problem with the thought that this "else" would include all the characters (because I have already included all the numbers on what to do so the thing that remains are the characters) and so, if somebody gave a character the the ERROR message would be shown and then the program would exit (because of the break; after the printf) something that never happens....
Can you please help me solve this problem? Thanks

[giammy]

Hi,

the line:
scanf("%d",&a);
read a digit: if you insert a letter, it gives error!

you should check, something like

if (scanf("%d",&a) == 1) {
do my thing
} else {
you insert a letter
}

see the manual for scanf behaviour (it returns the decoded input: 1
if it decodes an integer, 0 if it see a letter)

bye
giammy

[hakermania]

Hi,

the line:
scanf("%d",&a);
read a digit: if you insert a letter, it gives error!

you should check, something like

if (scanf("%d",&a) == 1) {
do my thing
} else {
you insert a letter
}

see the manual for scanf behaviour (it returns the decoded input: 1
if it decodes an integer, 0 if it see a letter)

bye
giammy

Well, I did'nt get you so, if it is not tiring for you could you rewrite my program with th things you told me? In that way I will understand it much better!

[giammy]

#include <stdio.h>
#include <stdlib.h>

int main()
{
int a;
while (1){
printf("If you are not root, please become...\n\n 1 = What's my mac? 7 = Start aircrack-ng and hack them all\n 2 = Change my mac 8 = Send DeAth to broadcast\n 3 = Start capturing IVS 9 = See available modems\n 4 = Start Reading files 10 = What's my interface? \n 5 = Stop interface 11 = About this prog \n 6 = Start interface 12 = Exit \n");
if (scanf("%d",&a) != 1) continue;
if (a==1) system("/etc/macchanger1.sh");
else if (a==2) system("/etc/macchanger2.sh");
else if (a==3) system("/etc/dumpcapt.sh");
else if (a==4) system("/etc/aireplayread.sh");
else if (a==5) system("/etc/airmonstop.sh");
else if (a==6) system("/etc/airmonstart.sh");
else if (a==7) system("/etc/aircrack.sh");
else if (a== system("/etc/aireplaysenddeath.sh");
else if (a==9) system("/etc/airodump-ng.sh");
else if (a==10) system("/etc/airmon-ng.sh");
else if (a==11) printf(" This prog was written on February 2010 with purpose to make your life easier\n in hacking yours WEP modems...Cheers!!!\n Note that you must have installed macchanger and aircrack-ng \n");
else if (a==12) break;
else if (a<=1 || a>=12) printf("Please type a number from 1 to 12\n");
else {printf("ERROR\n"); break;}
}
return 0;

}

[hakermania]

#include <stdio.h>
#include <stdlib.h>

int main()
{
int a;
while (1){
printf("If you are not root, please become...\n\n 1 = What's my mac? 7 = Start aircrack-ng and hack them all\n 2 = Change my mac 8 = Send DeAth to broadcast\n 3 = Start capturing IVS 9 = See available modems\n 4 = Start Reading files 10 = What's my interface? \n 5 = Stop interface 11 = About this prog \n 6 = Start interface 12 = Exit \n");
if (scanf("%d",&a) != 1) continue;
if (a==1) system("/etc/macchanger1.sh");
else if (a==2) system("/etc/macchanger2.sh");
else if (a==3) system("/etc/dumpcapt.sh");
else if (a==4) system("/etc/aireplayread.sh");
else if (a==5) system("/etc/airmonstop.sh");
else if (a==6) system("/etc/airmonstart.sh");
else if (a==7) system("/etc/aircrack.sh");
else if (a== system("/etc/aireplaysenddeath.sh");
else if (a==9) system("/etc/airodump-ng.sh");
else if (a==10) system("/etc/airmon-ng.sh");
else if (a==11) printf(" This prog was written on February 2010 with purpose to make your life easier\n in hacking yours WEP modems...Cheers!!!\n Note that you must have installed macchanger and aircrack-ng \n");
else if (a==12) break;
else if (a<=1 || a>=12) printf("Please type a number from 1 to 12\n");
else {printf("ERROR\n"); break;}
}
return 0;

}

hmmmm thx soooo much but I did it like this and works as well!!!:


#include <stdio.h>
#include <stdlib.h>

int main()
{
char tst[256];
int a;
while (1){
printf("If you are not root, please become...\n\n 1 = What's my mac? 7 = Start aircrack-ng and hack them all\n 2 = Change my mac 8 = Send DeAth to broadcast\n 3 = Start capturing IVS 9 = See available modems\n 4 = Start Reading files 10 = What's my interface? \n 5 = Stop interface 11 = About this prog \n 6 = Start interface 12 = Exit \n");
if (scanf("%d",&a)==1){
if (a==1) system("/etc/macchanger1.sh");
else if (a==2) system("/etc/macchanger2.sh");
else if (a==3) system("/etc/dumpcapt.sh");
else if (a==4) system("/etc/aireplayread.sh");
else if (a==5) system("/etc/airmonstop.sh");
else if (a==6) system("/etc/airmonstart.sh");
else if (a==7) system("/etc/aircrack.sh");
else if (a== system("/etc/aireplaysenddeath.sh");
else if (a==9) system("/etc/airodump-ng.sh");
else if (a==10) system("/etc/airmon-ng.sh");
else if (a==11) printf(" This prog was written on February 2010 by Hakermania\n a 15 years old child with purpose to make your life easier\n s modems...Cheers!!!\n Note that you must have installed macchanger and aircrack-ng \n Contact me:\n");
else if (a==12) break;
else if (a<=1 || a>=12) printf("Please type a number from 1 to 12\n");}
else {printf("ERROR do not type characters, please type a number from 1 to 12\n"); scanf("%s",tst);}
}
return 0;

}


But, anyway, thx for the help!!!