版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/asdasd3418/article/details/78814111
字符转数字
问题:
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.
翻译:
实现atoi(c语言的字符串转数字函数)将字符串转换为整数
仔细的考虑所有可能出现的情况。
解题方案:
这道题感觉出的不是很好,提示给的不够。代码比较容易,主要考虑越界的情况。
public int myAtoi(String str) {
if (str == null || str.trim().length() == 0) return 0;
str = str.trim();
int result = 0;
int flag = 1;
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (i == 0) {
if (c == '+') {
} else if (c == '-') {
flag = -1;
} else if (c >= '0' && c <= '9') {
result = result * flag + (c - '0') * flag;
} else {
return 0;
}
} else {
if (c >= '0' && c <= '9') {
int before = result;
result = result * 10 + (c - '0') * flag;
if (before > 0 && (Integer.MAX_VALUE - (c - '0') * flag) / 10 < before) {
return Integer.MAX_VALUE;
}
if (before < 0 && (Integer.MIN_VALUE - (c - '0') * flag) / 10 > before) {
return Integer.MIN_VALUE;
}
} else {
break;
}
}
}
return result;
}