Breaking down massive numbers

[iiwhitexb0iii]

I have ideas for the remainder of the program its just getting over the first hump that I need help with.

I am required to scan in long numerical values from an input file and multiply/add them together. When I assign integar variables to the numbers, one of them doesn't output properly (Its whereabouts of 16 digits long).

So I was forced to scan them in using a string. My question to you is this, is there any way to break down a numerical string into individual integars so I can manipulate them using stacks?

I've ran across strtok() as my only viable option thus far, but I don't know what to set as the tokenizer...I believe thats what its called. So naturally that won't work for me.

My hope to you is that someone can point me in any sort of direction so I can continue on with this program.

Thank you very much in advance.
-Michael

[quzah]

Subtract the character zero ( '0' ) from the current array index.

foo = array[ x ] - '0';

Quzah.

[Tonto]

Indexing operator.

char number[] = "1234567890";
int number_len, i, current;

number_len = strlen(number);
for(i = 0; i < number_len; ++i)
{
        current = number[i] - '0';
}

Should work on for ascii. If there are commas in it, and you wanted those little groupings, then strtok might be appropriate. Edit:

[swoopy]

>is there any way to break down a numerical string into individual integars so I can manipulate them using stacks?
It depends on how many digits you want per int. If you just want one digit per int, then you'd just use a for-loop, probably starting at the end to grab the lsb first:

   digit = num_string[i] - '0';

If you want three digits per int, you could use strlen to determine the length of the string and then strncpy to grab three digits, and store that in a temp string. Then use strtol or strtoul to convert from string to int.

[iiwhitexb0iii]

thank you all very much, i never would've thought about that on my own

-Michael

[iiwhitexb0iii]

i've used what you all have given me and its throwing up some errors. additionally, i should've mentioned this before hand, but i don't know exactly what i am recieving after subtracting '0' from the array index.

Assignment2.c: In function 'string_2_ints':
Assignment2.c:57: warning: passing argument 1 of 'strlen' from incompatible pointer type
Assignment2.c:60: error: invalid operands to binary -

i'm certain its an error on my end.
here are the necessary lines of code.

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

//Structure declaration
typedef struct    {
    char first [50];
    char second[50];
} data;

void string_2_ints(data numbers[], int num);

//Inside of main
data *numbers;

//num_sets is an integar variable scanned in from the input file
numbers = malloc(sizeof(data)*(num_sets * 2));

string_2_ints(numbers, num_sets);

//Seperate functions after main
void string_2_ints(data numbers[], int num)    {

    int i, length, digit;
    length = 0, digit = 0;

    length = strlen(numbers);

    for(i = 0; i < length; ++i)    {
        digit = numbers[i] - '0';
        printf("%d\n", digit);
    }
}

i apologize for any small errors inside the code as that was transcribed from a computer w/o internet access.

thank you for your time,
-Michael

[Dave_Sinkula]

Assignment2.c: In function 'string_2_ints':
Assignment2.c:57: warning: passing argument 1 of 'strlen' from incompatible pointer type
Assignment2.c:60: error: invalid operands to binary -

It's telling you that strlen needs a char*, not a data*. The char arrays in the struct perhaps?

[swoopy]

As Dave mentioned, you probably want to loop thru each string of the structure:

void string_2_ints(data numbers[], int num)    {

    int i, j, length, digit;
    length = 0, digit = 0;

    for (i=0; i<num; i++)
    {
        length = strlen(numbers[i].first);

        for(j = 0; j < length; ++j)    {
            digit = numbers[i].first[j] - '0';
            printf("%d\n", digit);
        }

        length = strlen(numbers[i].second);

        for(j = 0; j < length; ++j)    {
            digit = numbers[i].second[j] - '0';
            printf("%d\n", digit);
        }
    }
}

[swoopy]

>i don't know exactly what i am recieving after subtracting '0' from the array index.
What you're doing is subtracting '0' from the character's encoded value, in order to give you an int value from 0 to 9.

For example, assuming ascii encoding the hexadecimal values are:
'0' = 0x30
'1' = 0x31
'2' = 0x32
'3' = 0x33
'4' = 0x34
'5' = 0x35
'6' = 0x36
'7' = 0x37
'8' = 0x38
'9' = 0x39

Subtracting '0' (or 30 hexadecimal) from any of the above gives a value from 0-9, which is the int value.