题目：输入字符串，转变为对应整数
样式：输入"123",输出123
解法：遍历输出
private static int strToInt(String str) {
if (str == null) {
throw new IllegalArgumentException("str == null");
}
char[] chars = str.toCharArray();
boolean sign = true;
int index = 0;
if (chars[index] == '-') {
sign = false;
index++;
}
int result = 0;
for (; index < chars.length; index++) {
char num = chars[index];
if (num == ' ') {
continue;
}
num -= '0';
if (num > 0 && num < 9) {
if (sign && (result > Integer.MAX_VALUE / 10 ||
(result == Integer.MAX_VALUE / 10 && num > Integer.MAX_VALUE % 10))) {
result = Integer.MAX_VALUE;
break;
} else if (!sign && (result - 1 > Integer.MAX_VALUE / 10 ||
(result - 1 == Integer.MAX_VALUE / 10 && num > Integer.MAX_VALUE % 10))) {
result = Integer.MIN_VALUE;
break;
} else {
result = result * 10 + num;
}
} else {
throw new IllegalArgumentException("请输入数字");
}
}
return sign ? result : -result;
}
主要在于判断正负溢出情况
