java 把字串轉化成數字(不用JAVA系統函數)

public class Convert {public static void main(String[] args) {Convert convert = new Convert();int return_num = convert.convert_num("123");System.out.println("retunr nam --"+return_num);}/** *  把一組數字 字串轉化成數字 */public int convert_num (String val){int return_val = 0 ;char[] char_arr = val.toCharArray();for (int i = 0; i <char_arr.length; i++) {char c = char_arr[i];//例如： 100 = 10 *10 int  val_v = (int)Math.pow(10, char_arr.length-(i+1)); return_val =  return_val + (c-48) *val_v;}   return return_val;}}