请实现一个函数用来判断字符串是否表示数值（包括整数和小数）。例如，字符串"+100","5e2","-123","3.1416"和"-1E-16"都表示数值。 但是"12e","1a3.14","1.2.3","+-5"和"12e+4.3"都不是。
public class Solution54 {
private static int index=0;
public boolean isNumeric(char[] str) {
if(str.length > 0){
index= 0;
if(str[index] == ‘-‘ || str[index] == ‘+‘){
index ++;
}
if(index < str.length){
index = zhengshu(str);
if(index == str.length)return true;
if(str[index] == ‘.‘){
index ++;
if(index ==str.length) return false;
index = zhengshu(str);
if(index == str.length)return true;
if(str[index] == ‘.‘)return false;
else if(str[index] == ‘e‘ || str[index] == ‘E‘){
index ++;
if(index == str.length) return false;
if(str[index] == ‘+‘ || str[index] == ‘-‘){
index ++;
}
if(index == str.length) return false;
index = zhengshu(str);
if(index ==str.length) return true;
}else{
if(index == str.length)return true;
else return false;
}
}else if(str[index] == ‘e‘ || str[index] == ‘E‘){
index ++;
if(index == str.length) return false;
if(str[index] == ‘+‘ || str[index] == ‘-‘){
index ++;
}
if(index == str.length) return false;
index = zhengshu(str);
if(index ==str.length) return true;
}
return false;
}
}
return false;
}
private static int zhengshu(char[] str) {
while(index < str.length && str[index] >=‘0‘ && str[index]<=‘9‘){
index ++;
}
return index;
}
}
原文：http://www.cnblogs.com/chengpeng15/p/5820370.html