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I have to get a string of numbers of 2 digits separated by spaces, take the numbers out somehow and do operations with them. But the values are all going wrong, see for yourselves:

...
string = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08"; //example

for (int i = 0; i < string.size()-2; i += 3){
arr[i] = 10 * string[i] + string[i+1];      
cout << arr[i] <<' '<< 10 * string[i] <<' '<< string[i] << string[i+1] <<endl;
}

output:
536 480 08  i guess 0 times 10 isn't 480 as well as that plus 8 equals 536
530 480 02
550 500 22
625 570 97
566 510 38
543 490 15
528 480 00
568 520 40
528 480 00
603 550 75
532 480 04
533 480 05
535 480 07
606 550 78
580 530 52
540 490 12
578 530 50
605 550 77
619 570 91
536 480 08
Zeor137
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4 Answers4

2

You're doing your calculation with the ASCII values of the characters, not the numeric values of the digits. E.g. '0' is 48, '1' is 49, and so on.

for (int i = 0; i < string.size()-2; i += 3){
    arr[i] = 10 * (string[i]-'0') + (string[i+1]-'0');      
    cout << arr[i] <<' '<< 10 * string[i] <<' '<< string[i] << string[i+1] <<endl;
}
Barmar
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1

You're misunderstanding the int values you're retrieving. Just as an example, the 08 you're pulling.

'0' is not 0, it's 48
'8' is not 8, it's 56

48 * 10 + 56 = 536

instead of taking the ASCII representation of a character and using that in your calculations, use atoi.

Also, instead of going char by char you might want to look into the many ways to split a string of text in C++.

Community
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McAden
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0

Converting a character to an integer gives you the numeric value that represents the character; for the numeric digits, that's not the same as the value of the digit. Just about every computer you'll find these days uses ASCII coding, where '0' is represented by the value 48, '1' by 49, and so on.

You want to subtract the value that represents '0' so that '0' becomes 0, '1' becomes 1, and so on:

arr[i] = 10 * (string[i] - '0') + (string[i+1] - '0');
Mike Seymour
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-1

You could use the stoi()(string to integer) to convert your string to numerical values and then perform your operations.

user3314865
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