problem with file handling

Hi I have a txt file that I want my program to read. I use fstream. The file has the number 15 as the only thing in it. I want my program to read that 15 as an integer instead of a character string. Is that possible how do I convert a char string into an int. I know about typecasting but that doesn't work because it turns it into an integer that is huge and not the number 15. I think that is because it converts the string into the number of bits it took to store that string but I am not sure. So really my question is how do I get char thing[256]="15" to convert to int thingy = 15 ?
Am I making sense? Thank you.

This is the only way I can think of, you'll have to write the code yourself.
1. read the amount of digits in the string
2. read the numbers one at a time and convert entire string into a int array.
3. subtract 48 (value of zero as a char) from every number
4. multiply the number by multiples of 10 and add them.

"15\0" is the contents of you string
1. 2 digits
2. "49","54","\0"
3. "1","5","\0"
4. 1 (* 10(1)) + 5 (* 10(0))

Look the documentation for sscanf - it should do exactly what you want.

Eg. sscanf (mystring, "%d", &myint);

thanks i'll look into it

You could always use "atoi()" .... Array To Integer.

Code:

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#include <iostream>

using namespace std;

int main()
{
        char thing[256];

        sprintf(thing, "15");

        int thingy = atoi(thing); //array to integer

        cout << thingy << endl;

        return 0;
}

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Ah ha - ARRAY to integer - never could think of what the a was. HAHAHA :D .

Quote:

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Originally posted by gell10
I think that is because it converts the string into the number of bits it took to store that string but I am not sure.

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No. If you have this:

char * array = new char[256];

or this:

char array[256];

then "array", by itself, is a pointer to the first element of the array. So array is a variable that stores the memory address of the first element of the array. When you cast to an int, you get the address of the array.

Quote:

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Originally posted by gell10
I use fstream. The file has the number 15 as the only thing in it. I want my program to read that 15 as an integer instead of a character string.

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Come to think of it, isnt it simpler still to use:

int num;
in>>num; //assuming "in" is ifstream opened

i.e. read it as an integer straight away, rather than using atoi(), which I thought stood for "alpha to integer" rather than "array to integer".

what if i wanted it to find a word in the text file and then read the number that immediately follows it? would i use sscanf?