边界条件,注意传入的是否是非数字字符以及特殊符号之类的,+= 编译器强制进行了类型转换
public class StringDemo {
public static void main(String[] args) {
String s = "12345";
int sum=0;
int j=0;
for (int i = s.length()-1; i >= 0; i--) {
char c =s.charAt(i);
sum+=(c-'0')*(Math.pow(10, j));
j++;
}
System.out.println(sum);
//System.out.println(Math.p);
double d = 100;
int x= 0;
x+=0+3.0;
System.out.println();
}
}