Question:
Implement atoi to convert a string to an integer.
Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.
Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.
解决：
将字符串变为数字。需要注意坑很多。
public int myAtoi(String str) {
int sum = 0;
int flag = 1;
str = str.trim();
int i = 0;
if (str.length() == 0)
return sum;
if (str.charAt(0) == '-' || str.charAt(0) == '+'){
if (str.charAt(0) == '-')
flag = -1;
++i;
}
while(i < str.length() && Character.isDigit(str.charAt(i))){
if (judge(flag, sum, str.charAt(i)-'0')){
if (flag == 1)
sum = Integer.MAX_VALUE;
else
sum = Integer.MIN_VALUE;
break;
}
sum = sum * 10 + (str.charAt(i) - '0');
++i;
}
return flag == 1 ? sum : -sum;
}
public boolean judge(int flag, int sum, int digit){
boolean result = false;
if (flag == 1 && (sum > Integer.MAX_VALUE/10 || sum == Integer.MAX_VALUE/10 && digit > Integer.MAX_VALUE%10))
result = true;
if (flag == -1 && (-sum < Integer.MIN_VALUE/10 || -sum == Integer.MIN_VALUE/10 && -digit < Integer.MIN_VALUE%10))
result = true;
return result;
}
代码地址（附测试代码）：
https://github.com/shichaohao/LeetCodeUsingJava/tree/master/src/stringToInteger
