package com.test;public class AtoiTest {public static void main(String[] args) throws Exception {String s = "-011134";System.out.println("转换前的字符串：" + s);System.out.println("atoi1转换后的字符串：" + atoi1(s));System.out.println("atoi2转换后的字符串：" + atoi2(s));}/*** 不用java内置函数，将String字符串转换为数字* @param s* @return* @throws Exception */public static int atoi1(String s) throws Exception {if (s == null || s.length() == 0) {throw new Exception("要转换的字符串为空，无法转换！");}int retInt = 0;int[] num = new int[s.length()];for (int i = 0; i < s.length(); i++) {char c = s.charAt(i);switch (c) {case '-':num[i] = -1;break;case '0':num[i] = 0;break;case '1':num[i] = 1;break;case '2':num[i] = 2;break;case '3':num[i] = 3;break;case '4':num[i] = 4;break;case '5':num[i] = 5;break;case '6':num[i] = 6;break;case '7':num[i] = 7;break;case '8':num[i] = 8;break;case '9':num[i] = 9;break;default:throw new Exception("要转换的字符串格式错误，无法转换！");}}for (int i = 0; i < num.length; i++) {if (num[i] < 0 && i > 0) {throw new Exception("要转换的字符串格式错误，无法转换！");}if (num[i] < 0) {continue;}retInt += Math.pow(10, num.length - i - 1) * num[i];}if (num[0] == -1) {//代表负数retInt = -retInt;}return retInt;}/*** 不用java内置函数，将String字符串转换为数字* @param s* @return* @throws Exception*/public static int atoi2(String s) throws Exception{int retInt = 0;if (s == null || s.length() == 0) {throw new Exception("要转换的字符串为空，无法转换！");}boolean isNegative = false;for (int i = 0; i < s.length(); i++) {if (i==0) {if(s.charAt(i)=='-'){isNegative = true;continue;}}else{if(s.charAt(i)>'9' || s.charAt(i)<'0'){throw new Exception("要转换的字符串格式错误，无法转换！");}}retInt *=10;retInt += s.charAt(i) - '0';}return isNegative ? -retInt : retInt;}}
