i have a string of numbers, and i want to multiply these numbers
string myS = "731671765313";
int product = 1;
for(int i = 0; i<myS.length(); i++)
product *= myS[i];
How to convert the string element to int because the result is totally wrong. I tried casting it to int but in vain.
Use std::accumulate (because you're accumulating a product of elements, so it makes the intent clear) and recall that '0' is not 0, but that the digit characters are contiguous. For example, in ASCII, '0' is 48, '1' is 49, etc. Therefore, subtracting '0' will convert that character (if it's a digit) to the appropriate numerical value.
int product = std::accumulate(std::begin(s), std::end(s), 1,
[](int total, char c) {return total * (c - '0');}
);
If you can't use C++11, it's easily replaced:
int multiplyCharacterDigit(int total, char c) {
return total * (c - '0');
}
...
int product = std::accumulate(s.begin(), s.end(), 1, multiplyCharacterDigit);
If neither of those are an option, what you had is almost there:
int product = 1;
for(int i = 0; i<myS.length(); i++)
product *= (myS[i] - '0');
(int)'a'does? ;)(myS[i]-'0'), otherwise this is a duplicate and you should usestd::stoiatoi(myS[i])andstoi(myS[i])...... error