Simple error that i cant find... irritating me

Homestar · #1 30-Mar-2004, 01:00

ok when q is used to quit it prints out the intialized values of the rest of the array to 0... i dont want it to print these... also when the tenth integer is entered and the program ends the last integer entered is not printed but is initialized to 0 instead... any suggestions?.. im just trying to familiariz myself witht this stuff.. and this is being difficult.

CPP / C++ / C Code:

#include <stdio.h>
int x[10];
void main()
{
    int i;
    printf("Enter a list of up to 10 integers, q to quit.\n" );
    for (i = 0; i <= 9; i++)
    {
   
    scanf("%d\n", &x[i]);
    	
    }
    printf("Array in reverse order:\n " );
    for (i = 9; i >= 0; i--)
    {
    printf("%5d", x[i]);
    }
    printf("\n");

}

aaroncohn · #2 30-Mar-2004, 03:46

I'm not seeing where you have "q to quit" implemented in your code.

davekw7x · #3 30-Mar-2004, 08:41

Don't know about 'q' for quit, but heres a problem:

Change

CPP / C++ / C Code:

    scanf("%d\n", &x[i]);

to

CPP / C++ / C Code:

    scanf("%d", &x[i]);

When you have problems like this, I suggest you put a printf() after the place where you obtain user input (to make sure the program sees what you think it out to see).

For example

CPP / C++ / C Code:

scanf("%d", &x[i]);
printf("You entered: %d\n", x[i]);

" printf() is your friend."

Regards,

Dave

Homestar · #4 30-Mar-2004, 11:14

Quote:

Originally Posted by aaroncohn

I'm not seeing where you have "q to quit" implemented in your code.

There is no code for q to quit because none is needed.... anything besides an int value entered for scanf is not recognized and it stops.

Homestar · #5 30-Mar-2004, 11:15

Quote:

Originally Posted by davekw7x

Don't know about 'q' for quit, but heres a problem:

Change

CPP / C++ / C Code:

    scanf("%d\n", &x[i]);

to

CPP / C++ / C Code:

    scanf("%d", &x[i]);

When you have problems like this, I suggest you put a printf() after the place where you obtain user input (to make sure the program sees what you think it out to see).

For example

CPP / C++ / C Code:

scanf("%d", &x[i]);
printf("You entered: %d\n", x[i]);

" printf() is your friend."

Regards,

Dave

Ok but the problem is when im printing out everything in the end... i get all the user inputs fine but i just dont want the arrays that were not used to print out zero... how do i tell it only to print the arrays used...

davekw7x · #6 30-Mar-2004, 12:27

Quote:

Originally Posted by Homestar

Ok but the problem is when im printing out everything in the end... i get all the user inputs fine but i just dont want the arrays that were not used to print out zero... how do i tell it only to print the arrays used...

The program that you posted requires 10 entries then prints out 10 values. Your scanf() is expecting an integer. If the user enters anything that is not an integer, it goes back through the loop for a total of 10 times. Each time scanf() is still looking at the (non-integer) character in the input buffer, so doesn't store anything in the array. I guess that global variables are initialized to 0, so you see zeros in places for which you haven't given values.

This shows why lots of people say that scanf() is not very good for user input.

Dave

Homestar · #7 30-Mar-2004, 13:27

Quote:

Originally Posted by davekw7x

The program that you posted requires 10 entries then prints out 10 values. Your scanf() is expecting an integer. If the user enters anything that is not an integer, the goes back through the loop for a total of 10 times. Each time scanf() is still looking at the (non-integer) character in the input buffer, so doesn't store anything in the array. I guess that global variables are initialized to 0, so you see zeros in places for which you haven't given values.

This shows why lots of people say that scanf() is not very good for user input.

Dave

I figured it out... needed a while statement and stuff but i got it. Well if not using scanf() then what is better to use?.. any advice is helpful at my nub stage in this.

davekw7x · #8 30-Mar-2004, 13:38

Quote:

Originally Posted by Homestar

I figured it out... needed a while statement and stuff but i got it. Well if not using scanf() then what is better to use?.. any advice is helpful at my nub stage in this.

Lots of people use fgets() to get a complete line into a buffer, then sscanf(), atoi() or lots of other possibilities (including roll-your-own tests) for extracting numbers, characters, etc.

Dave

Homestar · #9 30-Mar-2004, 17:28

Quote:

Originally Posted by davekw7x

Lots of people use fgets() to get a complete line into a buffer, then sscanf(), atoi() or lots of other possibilities (including roll-your-own tests) for extracting numbers, characters, etc.

Dave

o ok thanx man

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