# Sharing my C# solution (94th percentile) for atoi

• This one took me forever to handle all of the cases. Probably would have missed some/many of them in a real interview, but anyway, I ended up with this solution which is apparently faster than 94% of all submitted solutions, so I feel OK about myself. Regardless, I think my solution is pretty hard to read and maybe a little convoluted, maybe someone else has a cleaner way of doing this?

``````public int MyAtoi(string str) {
if (str == null) {
return 0;
}

char[] chars = str.ToCharArray();
double result = 0;
int firstIndex = 0;
int lastIndex = chars.Length - 1;
bool isNegative = false;
bool foundSign = false;
bool foundDigits = false;
for (int i = 0; i < chars.Length; i++) {
if (!foundSign && (chars[i] == '-' || chars[i] == '+')) {
foundSign = true;
isNegative = chars[i] == '-';
} else if (chars[i] >= '0' && chars[i] <= '9') {
if (!foundDigits) {
foundDigits = true;
firstIndex = i;
}
lastIndex = i;
} else if (foundDigits && (chars[i] < '0' || chars[i] > '9')) {
break;
} else if (!foundSign && !foundDigits && chars[i] == ' ') {
continue;
} else {
return 0;
}
}

if (!foundDigits) {
return 0;
}

for (int i = lastIndex, pow = 0; i >= firstIndex; i--, pow++) {
int convertedDigit = (int)chars[i] - (int)'0';
result += Math.Pow(10, pow) * convertedDigit;
}

if (isNegative) {
result *= -1;
}

if (result > int.MaxValue) {
return int.MaxValue;
}

if (result < int.MinValue) {
return int.MinValue;
}

return (int)result;
}``````

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