请问用java怎么判断输入是否为数字和英文字母，如果不是就提示输入错误？ 在C语言中如何判断输入的是否为英文字母？
\u8bf7\u95ee\u7528java\u600e\u4e48\u5224\u65ad\u8f93\u5165\u662f\u5426\u4e3a\u6570\u5b57\u548c\u82f1\u6587\u5b57\u6bcd\uff0c\u5982\u679c\u4e0d\u662f\u5c31\u63d0\u793a\u8f93\u5165\u9519\u8bef\uff1f\u7528\u6b63\u5219\u8868\u8fbe\u5f0f\u5339\u914d\u3002
\u6bd4\u5982\u8f93\u5165\u4e3aString
s\uff0cs.matches("[0-9a-zA-Z]*")\u8fd4\u56detrue\uff0c\u5c31\u53ef\u4ee5\u4e86\uff5e
\uff1a#include
isalnum() \u7528\u6765\u5224\u65ad\u4e00\u4e2a\u5b57\u7b26\u662f\u5426\u4e3a\u82f1\u6587\u5b57\u6bcd\u6216\u6570\u5b57\uff0c\u76f8\u5f53\u4e8e isalpha(c) || isdigit(c)\uff0c\u5176\u539f\u578b\u4e3a\uff1a
int isalnum(int c);
\u3010\u53c2\u6570\u3011c \u4e3a\u9700\u8981\u68c0\u6d4b\u7684\u5b57\u7b26\u3002
\u3010\u8fd4\u56de\u503c\u3011\u82e5\u53c2\u6570c \u4e3a\u5b57\u6bcd\u6216\u6570\u5b57\uff0c\u82e5 c \u4e3a 0 ~ 9 a ~ z A ~ Z \u5219\u8fd4\u56de\u975e 0\uff0c\u5426\u5219\u8fd4\u56de 0\u3002\u6ce8\u610f\uff0cisalnum()\u4e3a\u5b8f\u5b9a\u4e49\uff0c\u975e\u771f\u6b63\u51fd\u6570\u3002
\u3010\u5b9e\u4f8b\u3011\u627e\u51fastr \u5b57\u7b26\u4e32\u4e2d\u4e3a\u82f1\u6587\u5b57\u6bcd\u6216\u6570\u5b57\u7684\u5b57\u7b26\u3002
#include main(){char str[] = "123c@#FDsP[e?";int i;for (i = 0; str[i] != 0;
i++)if(isalnum(str[i]))printf("%c is an alphanumeric character\n", str[i]);}
#include
main(){
char str[] = "123c@#FDsP[e?";
int i;
for (i = 0; str[i] != 0; i++)
if(isalnum(str[i]))
printf("%c is an alphanumeric character\n", str[i]);}
\u8f93\u51fa\u7ed3\u679c\uff1a1 is an apphabetic character
2 is an apphabetic character
3 is an apphabetic character
c is an apphabetic character
F is an apphabetic character
D is an apphabetic character
s is an apphabetic character
P is an apphabetic character
e is an apphabetic character
比如输入为String s，s.matches("[0-9a-zA-Z]*")返回true，就可以了～
(1)字符串操作，获得密码框里的字符，分割开....（2）判断每次输入时按下的键值【ASCII码】（3）正则表达式。提倡（3）。
可以根据 国际标准码 判断
这里的输入指的是从哪里输入呢？？？流？？输入框（b/c）？？
绛旓細import java.util.Scanner;public class Io { public static void main(String[] args){ Scanner s = new Scanner(System.in);System.out.println("input your data: ");if(s.hasNext())System.out.println(s.nextInt());s.close();} } ...
绛旓細a System.out.println("a"); } else if ("鍚".equals(answer)) { // do some thing for b System.out.println("b"); } else { System.out.println("杈撳叆閿欒"); } }}
绛旓細浣犻渶瑕佹妸if (yes==input) 鍜宨f (no==input) 鏀规垚 if锛坹es.equals锛坕nput锛夛級鍜宨f锛坣o.equals锛坕nput锛夛級銆傚洜涓轰綘瑕佹瘮杈冪殑鏄粬浠袱涓彉閲忔墍瀛樺偍鐨勫唴瀹鏄惁鐩稿悓鑰屼笉鏄瘮杈冧粬浠袱涓槸鍚︽寚鍚戝悓涓涓唴瀛樺湴鍧锛屾墍浠ラ渶瑕佺敤equals锛堬級鏂规硶銆
绛旓細if(l==""){ System.out.print("韬唤璇佸彿鐮佷笉鑳戒负绌猴紒");} else if(l.length()<19&&l.length()>17){ System.out.print("浣杈撳叆鐨18涓鸿韩浠借瘉鍙风爜涓猴細"+l);} else { System.out.print("浣犺緭鍏ョ殑韬唤璇佷綅鏁颁笉姝ｇ‘锛");} } } 涓婇潰浠ｇ爜锛屽彲浠ヨ繍琛屾垚鍔燂紝鍔熻兘锛1銆鍒ゆ柇鏄惁鏈夎緭鍏ワ紱2銆...
绛旓細鐢ㄦ鍒欒〃杈惧紡鍖归厤銆傛瘮濡杈撳叆涓篠tring s锛宻.matches("[0-9a-zA-Z]*")杩斿洖true锛屽氨鍙互浜嗭綖
绛旓細棰樹富鐨勯棶棰樺ぇ浣撳氨鏄濡備綍鍒ゆ柇鐢ㄦ埛鐨杈撳叆鏄惁鍚堟硶銆傝繖閲屾渶鏂逛究鐨勫氨鏄浣跨敤姝ｅ垯琛ㄨ揪寮忥紙Regular Expression锛岀畝绉 Regex锛夈傛鍒欒〃杈惧紡鏄竴涓瓧绗︿覆锛屽畠浠ｈ〃鐨勬槸涓瀹氱殑瀛楃涓叉ā寮忥紙姣斿閭鐨勬ā寮忓氨鏄 "鏁板瓧鎴栧瓧姣 + @ + 鏁板瓧鎴栧瓧姣 + . + 椤剁骇鍩熷悕鍚嶇О"锛夛紝褰撶敤鎴疯緭鍏ヤ竴涓瓧绗︿覆鏃讹紝绗﹀悎杩欎釜妯″紡鐨勫瓧绗︿覆...
绛旓細//绗竴涓暟System.out.println("璇杈撳叆绗竴涓暟銆");double n1=0;double n2=0;for (int i = 1; i <= 4; i++) {Scanner scanforn1 = new Scanner(System.in);if(scanforn1.hasNextDouble()==false) {if(i==4) {System.out.println("鎮ㄨ緭鍏ョ殑娆℃暟杩囧锛岀▼搴忕粨鏉");System.exit(...
绛旓細瀛楃涓叉瘮杈 浣跨敤.equals();\x0d\x0aString s1 = "aaa"; //杈撳叆瀛楃涓瞈x0d\x0aString s2 = "bbb"; //鍥哄畾瀛楃涓瞈x0d\x0aSystem.out.println(s1.equals(s2));\x0d\x0a\x0d\x0a瀛楃涓叉瘮杈冧笉瑕佷娇鐢 ==\x0d\x0a鍥犱负浣跨敤== 姣旇緝鐨勪袱涓瓧绗︿覆鐨勫紩鐢鏄惁鐩哥瓑 \x0d\x0a...
绛旓細姝ｅ垯琛ㄨ揪寮忥細System.out.print("Enter customer type (r/c): ");String customerType = sc.next();String reg = "^(r|c|R|C){1}$";if(!customerType.matches(reg)){System.out.println("Error , please try again !");}else{System.out.println("Congratulations!");} ...
绛旓細浣犲彲浠ョ敤try{}catch鏉ュ鐞嗭紝濡傛灉杞崲鐨勬椂鍊欏嚭閿欎簡锛岄偅灏辫偗瀹氫笉鏄暟瀛
