Trying to create a simple array program

**cyberjupiter** · 09-15-2017

Hi all.

Okay so first some explanation of the program.

1. When user input some text and press enter, the program saves the array and the newline. The chars entered should be less than 10 including the newline.

2. The input is saved into a storage that contains a maximum of 1000 chars.

3. The program print the storage. The storage should look like this

Code:

array1
array2
array3
array4
and so on..

Here's what I got so far

Code:

#include <stdio.h>

int main()
{
    
    char buffer[10];
    char storage[1000];
    int index = 0;
    int holder;
    int i = 0;

    holder = getchar();
    while (holder != EOF)
    {
        buffer[index] = holder;
        index++;
        
        if (holder == '\n')
        {
            for (i = 0; i < 1000; i++)
            {
                storage[i] = buffer[i];
            }
        }
    }
    
    storage[i] = '\0';
    
    printf("%s", storage);
}

The program stops working after i input some text.

Any idea?

**stahta01** · 09-16-2017

buffer is only 10 chars long; you are trying to copy 1000 chars from it. This results in undefined behavior.

Edit: And, the line below; write a zero byte beyond the end of the storage since i = 1000 is past the end.

Code:

storage[i] = '\0';

Hint: Lookup fgets and strcpy functions.
This problem is likely designed to use fgets() and might be designed to use one of the str... functions.

Tim S.

**cyberjupiter** · 09-16-2017

Originally Posted by stahta01

buffer is only 10 chars long; you are trying to copy 1000 chars from it. This results in undefined behavior.

Edit: And, the line below; write a zero byte beyond the end of the storage since i = 1000 is past the end.

Code:

storage[i] = '\0';

Hint: Lookup fgets and strcpy functions.
This problem is likely designed to use fgets() and might be designed to use one of the str... functions.

Tim S.

I want to avoid using any str functions if possible.

Anyway here's I am now

Code:

#include <stdio.h>

int main()
{
    char buffer[10];
    char storage[1000];
    int index = 0;
    int holder;
    int i = 0;
    int newidx = 0;

    while((holder = getchar()) != EOF)
    {
        buffer[index] = holder;
        index++;
        if (holder = '\n')
        {
            buffer[index] = holder;
            for (i = 0; i < index; i++ )
            {
                storage[i + newidx] = buffer[i];
            }
        newidx = i + newidx;
        index = 0;
        }
    }
    storage[newidx] = '\0';    
    printf("%s", storage);   
}

It works but there's one problem. The buffer should not accept more than 10 chars. For example, if I input "123456789ab", 'b' should be omitted because it exceeds 10 chars(I might be wrong here, please correct me). But it does not work like that.

**cyberjupiter** · 09-17-2017

UPDATE:

So I have restructured my code and it's working.

Code:

#include <stdio.h>

int main()
{
    char buffer[10];
    char storage[1000];
    int index = 0;
    int holder;
    int i = 0;
    int newidx = 0;

    
    while((holder = getchar()) != EOF) //while the input is not = end of file. holder will only hold one char every reading
    {
        if (holder == '\n') //if the input is = newline character
        {
            if (index > 10) //if the index is more than 10, we set the index to a max of 10 only
            {
                index = 10;
            }
            
            if (index <= 10) //this code is executed because index is now less or equal to 10
            {
            buffer[index] = holder; //the last index should equal to newline because we want to store the newline per char array
                for (i = 0; i <= index; i++ )
                {
                    storage[i + newidx] = buffer[i]; //this code will always store buffer[] into the last newidx value of storage[]
                }    
            newidx = i + newidx; //update the newidx value
            index = 0; //clear the index as we want to receive new char array again
            }
        }        
        
        else //as long the first input is other than newline, this part will get executed first            
        { 
            buffer[index] = holder; //every char is put into buffer[] except newline
            index++;
        }
    }
    
    storage[newidx] = '\0'; //char array is always terminated with NULL to indicate end of string
    printf("%s", storage); //print everything inside storage[]. it is always printed from the first which is [0]
}

But I would like to hear comments from folks.

**Asymptotic** · 09-17-2017

This program is wacky. Just from a user's perspective, I just built it with GCC and ran it and first of all, I typed more than 10 chars and it crashed. I'm guessing segfault but didn't formally check.

Secondly, even when I did conform to the less than 10 char guideline, it seems to just collect input forever and never displays it. Maybe it does, but eve if I enter a blank line, it keeps trying to get lines... Is this how you intended it to work?

You need to add some sort of check to make sure that the input is 10 or less lines and if not, discard it and perhaps warn the user rather than allow the program to crash like that. Even if that's not part of the assignment, nobody wants a program to segfault like that.

**cyberjupiter** · 09-17-2017

Thanks Asymptotic. I really value your thoughts. But it didn't crash(yet) for me? Nevermind anyway, I will try until it crashes.

Secondly, I never set any spec for this program. What I wanted to do is to have the user input some text which is less than 10 chars, press enter(newline) to input next text and press EOF to display all input text in the form of

Code:

text1
text2
text3

What I wanted to learn is how to store a char array("buffer" as in program) to another char array("storage" as in program). But "buffer" must be stored into the consecutive space of "storage". And the program did.

That's all I wanted for now.

**~~userxbw~~** · 09-21-2017

mmmm somethig like this perhaps

Code:

#include <stdio.h>
int main (int argc, char **argv)
{

char store[10];
char hold[1000];
int i = 0 , j = 0, k = 0;

while( i  < 4)
{

    //store whatever
    for(j = 0 ; j <4; j++)
    {
        store[j] = getchar();
        printf("%c\n", store[j]);
        printf("j = %d\n",  j);
    }
 
//shove it into the holding array
     hold[i] = store[10];
    printf("i = %d\n", i );
    i++;
}
//print it out
int e = 0; 
for ( e = 0; e < 5; e++)
{

        printf("%d\n", e);
}


return 0;
}

you have to fill each array1[10] first then put that into another array2[1000]; when full or on demand then print it out. inner loops controls the 10 lenth limit for each array, the outer loop controls the max limit of 1000 elements of storage[10].

if using the same array which you should/could, you'll need to clear it first before using it again.

that array[10] holds the input off cli then the other array[1000] holds the the input 10 count ch length each.

Code:

array1[1000];
array2[10]

fill array2[10] 

assign it to array1 elements

array1[0] = arrary2[10]

clear array2[10]

for (i = 0 ; i < array2.length; i++)
    array2[i] = 0;

fill array2[10] again

assign it to the next element 
array1[1] = array2[10]

repeat until finished

then print it out when done/ or on demand

that may or may not work because it is using the same array,
I'm not sure of the the values what would be in the array1 element will be as expected. but that is the basic logic behind it.

two loops:

Code:

int j = 0, k = 0;

while (k < 4)
{
    for (j = 0; j < 5; j++)
    {
        printf("in j = %d\n", j);
    }
    printf("while k = %d\n",k);
    k++;
}
printf("out of while\n");

**cyberjupiter** · 09-21-2017

Thanks @userxbw.

Your example works great too! Eventhough mine is good enough for now, yours can be used as future reference.

**~~userxbw~~** · 09-22-2017

Originally Posted by cyberjupiter

Thanks @userxbw.

Your example works great too! Even though mine is good enough for now, yours can be used as future reference.

#4 you can live with that?
run this:

Code:

#include <stdio.h>

int main()
{
    char buffer[10];
    char storage[1000];
    int index = 0;
    int holder;
    int i = 0;
    int newidx = 0;


    while((holder = getchar()) != EOF) //while the input is not = end of file. holder will only hold one char every reading
    {
        if (holder == '\n') //if the input is = newline character
        {
            if (index > 10) //if the index is more than 10, we set the index to a max of 10 only
            {
                index = 10;
            }

            if (index <= 10) //this code is executed because index is now less or equal to 10
            {
                buffer[index] = holder; //the last index should equal to newline because we want to store the newline per char array
                for (i = 0; i <= index; i++ )
                {
                    printf("newidx %d, i %d , index %d \n", newidx, i, index);
                    storage[i + newidx] = buffer[i]; //this code will always store buffer[] into the last newidx value of storage[]
                }
            newidx = i + newidx; //update the newidx value
            index = 0; //clear the index as we want to receive new char array again
            }
        }

        else //as long the first input is other than newline, this part will get executed first
        {
            buffer[index] = holder; //every char is put into buffer[] except newline
            index++;
            printf("index %d \n", index);
        }
    }

    storage[newidx] = '\0'; //char array is always terminated with NULL to indicate end of string
    printf("%s", storage); //print everything inside storage[]. it is always printed from the first which is [0]
}

look at your values and see what your index is doing then look at your code again.

Code:

index 119 
newidx 1717660002, i 0 , index 10 
Segmentation fault

**~~userxbw~~** · 09-22-2017

something to start with:

Code:

#include <stdio.h>

int main()
{
    char buffer;
    char storage[10];
     int keepCount = 0, i = 0;

    while( keepCount <  (sizeof(storage)/sizeof(storage[0]) ) )
    {
            buffer = getchar();
            printf(" you did this ");
            storage[keepCount] = buffer;
            putchar(buffer);
            printf("\n");
            keepCount++;

    } // end while

    for ( i = 0; i < 10; i++)
        printf("%c \n", storage[i]);

    return 0 ;
}

output

Code:

userx@~/bin <> gcc -Wall buffy.c
userx@~/bin <> ./a.out
123456789101112131415
 you did this 1
 you did this 2
 you did this 3
 you did this 4
 you did this 5
 you did this 6
 you did this 7
 you did this 8
 you did this 9
 you did this 1
1 
2 
3 
4 
5 
6 
7 
8 
9 
1 
userx@~/bin <>

**cyberjupiter** · 09-22-2017

Well then you didn't clearly understand what I was trying to do. Your last example does not meet the spec I stated in my #1 post.

**~~userxbw~~** · 09-22-2017

Originally Posted by cyberjupiter

Well then you didn't clearly understand what I was trying to do. Your last example does not meet the spec I stated in my #1 post.

if it worked properly I'd not be able to blow it up. you're not checking for over flow on your char[1000], your index++ is not working correctly. look
your code again adding something to show and tell something else as well.
what ever it is it is not working properly,

Code:

#include <stdio.h>

int main()
{
    char buffer[10];
    char storage[10];
    int index = 0;
    int holder;
    int i = 0;
    int newidx = 0;


    while((holder = getchar()) != EOF) //while the input is not = end of file. holder will only hold one char every reading
    {
        if (holder == '\n') //if the input is = newline character
        {
            if (index > 10) //if the index is more than 10, we set the index to a max of 10 only
            {
                index = 10;
            }

            if (index <= 10) //this code is executed because index is now less or equal to 10
            {
                buffer[index] = holder; //the last index should equal to newline because we want to store the newline per char array
                for (i = 0; i <= index; i++ )
                {
                    printf("newidx %d, i %d , index %d \n", newidx, i, index);
                    storage[i + newidx] = buffer[i]; //this code will always store buffer[] into the last newidx value of storage[]
                }
            newidx = i + newidx; //update the newidx value
            index = 0; //clear the index as we want to receive new char array again
            }
        }

        else //as long the first input is other than newline, this part will get executed first
        {
            buffer[index] = holder; //every char is put into buffer[] except newline
            index++;
            printf("index %d \n", index);
        }
        }
   storage[newidx] = '\0'; //char array is always terminated with NULL to indicate end of string
    printf("Storage: %s", storage); //print everything inside storage[]. it is always printed from the first which is [0]
    }

    storage[newidx] = '\0'; //char array is always terminated with NULL to indicate end of string
    printf("Not mine storage:  %s", storage); //print everything inside storage[]. it is always printed from the first which is [0]


    return 0;
}

storage never gets printed?
taking it down to 10 to show you something.
output look at index?

if you ever reached that 1000 it'd blow up.

and your last two lines of code are in the wrong place that is why they never get printed out.

Code:

userx@~/bin <> ./a.out
12345678901234567890
index 1 
index 2 
index 3 
index 4 
index 5 
index 6 
index 7 
index 8 
index 9 
index 10 
index 11 
index 12 
index 13 
index 14 
index 15 
index 16 
index 17 
index 18 
index 19 
index 20 
newidx 0, i 0 , index 10 
newidx 0, i 1 , index 10 
newidx 0, i 2 , index 10 
newidx 0, i 3 , index 10 
newidx 0, i 4 , index 10 
newidx 0, i 5 , index 10 
newidx 0, i 6 , index 10 
newidx 0, i 7 , index 10 
newidx 0, i 8 , index 10 
newidx 0, i 9 , index 10 
newidx 0, i 10 , index 10 
^C
userx@~/bin <> gcc -Wall buffynotgood.c
userx@~/bin <> ./a.out
123456789012345678901234567890
index 1 
Storage: index 2 
Storage: index 3 
Storage: index 4 
Storage: index 5 
Storage: index 6 
Storage: index 7 
Storage: index 8 
Storage: index 9 
Storage: index 10 
Storage: index 11 
Storage: index 12 
Storage: index 13 
Storage: index 14 
Storage: index 15 
Storage: index 16 
Storage: index 17 
Storage: index 18 
Storage: index 19 
Storage: index 20 
Storage: index 21 
Storage: index 22 
Segmentation fault
userx@~/bin <>

**cyberjupiter** · 09-22-2017

The sad news for you, storage does get printed out using my code.

Look, I have stated in my first post this is a "simple array program". Re-read #6. I never intended to check for overflow in the first place.

And again, your last post is not even doing what I expected but mine did

**~~userxbw~~** · 09-22-2017

something more like this but you still got to figure out how to get a array[size] inside another array element

Code:

char array1[10];
char array2 [10];

array2[0] = array1[0];
arrary2[1] = array1[1];

getchar only gets one char at a time and not a string to fill 

array2[0] = array1[0] = 'bob';

Code:

#include <stdio.h>
/*
 *

Join Date
    Sep 2017
Posts
    14

Trying to create a simple array program

    Hi all.

    Okay so first some explanation of the program.

    1. When user input some text and press enter, the program saves the array and the newline. The chars entered should be less than 10 including the newline.

    2. The input is saved into a storage that contains a maximum of 1000 chars.

    3. The program print the storage. The storage should look like this
    * **/


int main()
{
char c;
char holdme[5];

int i = 0, count = 0, check = 0, move1atatime = 0;

while ( move1atatime < ( sizeof(holdme)/sizeof(holdme[0]) )  )
{
         c  = getchar();

    if ( check != 4 )
    {
            holdme[move1atatime] = c;
            holdme[move1atatime + 1] = '\0'; // to allow 10th to be \0
            check++;
    }
    else
    {
        check = 0; // fills each element up to 10 --1 for eof
        move1atatime++; // moves  element limit is sizeof(array)
        printf(" count %d move1atatime %d \n",  count, move1atatime);
    }
}

for ( i = 0; i < sizeof(holdme)/sizeof(holdme[0] ) ;  i++)
    printf("%c \n ", holdme[i]);


return 0;
}

**~~userxbw~~** · 09-22-2017

this one does exactly MORE then what you want because it does not over running the arrays. All that needs be done is ........ , and,it is using only one line with a lot less code then yours.

Trying to create a simple array program

Hi all.

Okay so first some explanation of the program.

1. When user input some text and press enter, the program saves the array and the newline. The chars entered should be less than 10 including the newline.

2. The input is saved into a storage that contains a maximum of 1000 chars.

3. The program print the storage. The storage should look like this

Code:

array1
array2
array3
array4
and so on..

Code:

#include <stdio.h>
#include <string.h>
int main() {char cheery[10]; char *holdme[5]; int i = 0, move1atatime = 0; while ( move1atatime < ( sizeof(holdme)/sizeof(holdme[0]))) { scanf("%9s" ,cheery);  holdme[move1atatime] =  strdup (cheery); move1atatime++; } for ( i = 0; i < sizeof(holdme)/sizeof(holdme[0] ) ;  i++) printf("\ncount %d :: %s \n ", i, holdme[i] ); return 0; }

Results

Code:

 userx@~/bin <> ./a.out 
abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz

count 0 :: abcdefghi 
 
count 1 :: jklmnopqr 
 
count 2 :: stuvwxyza 
 
count 3 :: bcdefghij 
 
count 4 :: klmnopqrs 
 userx@~/bin <>

see it does not blow up if you over run it with chars.
now
post your output off your program.

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