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Copy path008_stringToInteger.cpp
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62 lines (58 loc) · 1.49 KB
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/*@Description: String to Integer (atoi)
Implement atoi to convert a string to an integer.
*/
/*处理四种情况：开头连续的空格；正负符号；不合理的输入；溢出
不合理的输入"+-123"、"- 123"、"b123"等均输出0，"123a"这种情况输出前面的合理数字123
*/
class Solution {
public:
int myAtoi(string str) {
double result = 0;
int i = 0, flag = 0;
while(str[i] == ' ')
i++;
if(str[i] == '-')
{
flag = 1;
i++;
}
else if(str[i] == '+')
{
i++;
}
for(; i < str.size(); i++)
{
if(str[i] > '9' || str[i] < '0')
break;
result = result * 10 + str[i] - '0';
}
if(flag)
result = -result;
if(result > INT_MAX)
result = INT_MAX;
if(result < INT_MIN)
result = INT_MIN;
return (int)result;
}
};
int myAtoi(string str)
{
int sign = 1, base = 0, i = 0;
while (str[i] == ' ') { i++; }
if (str[i] == '-' || str[i] == '+')
{
sign = 1 - 2 * (str[i++] == '-');
}
while (str[i] >= '0' && str[i] <= '9')
{
if (base > INT_MAX / 10 || (base == INT_MAX / 10 && str[i] - '0' > 7))
{
if (sign == 1)
return INT_MAX;
else
return INT_MIN;
}
base = 10 * base + (str[i++] - '0');
}
return base * sign;
}