package LeetCode.String.stringToInt;
public class Solution {
public int myAtoi(String str) {
double num = 0;
for(int i = 0;i < str.length();i++) {
//判断第一个非空格字符是否为数字或者'-'
if (str.charAt(i) != ' ' && ((str.charAt(i) == '-' || str.charAt(i) == '+')|| (str.codePointAt(i) >= 48 && str.codePointAt(i) <= 57))) {
//如果第一个非空格字符是'-'但是'-'后不是数字，直接返回0
if (i 57)) {
num = 0;
break;
}
else if (str.charAt(i) == '-') {
for (int j = i + 1; j < str.length() && (str.codePointAt(j) >= 48 && str.codePointAt(j) <= 57); j++) {
num = (num * 10 + Integer.parseInt(str.substring(j,j+1)));
}
num = (-1) * num;
break;
}else if (i 57)) {
num = 0;
break;
}else if(str.charAt(i) == '+'){
for (int j = i+1;j < str.length() && (str.codePointAt(j) >= 48 && str.codePointAt(j) <= 57) ; j++) {
num = (num * 10 + Integer.parseInt(str.substring(j,j+1)));
}
break;
}else{
for (int j = i;j < str.length() && (str.codePointAt(j) >= 48 && str.codePointAt(j) <= 57) ; j++) {
num = (num * 10 + Integer.parseInt(str.substring(j,j+1)));
}
break;
}
} else if (str.charAt(i) != ' '){
num = 0;
break;
}
}
return (int)num;
}
}