Question

java编程出现The operator >= is undefined for the argument type(s) char[], char的错误

package lianxi01;
import java.util.*;
public class test07 {
public static void main(String[] args){
int digital=0;
int character=0;
int other=0;
int blank=0;
char[] ch=null;
Scanner sc;
String s =sc.nextLine();
ch=s.toCharArray();
for(int i=0;i<ch.length;i++)
{
if(ch>='0'&&ch<='9'){
digital++;
}
else if((ch>='a'&&ch<='z')||ch>'A'&&ch<='Z'){
character++;
}
else if(ch==' '){
blank++;
}else{
other++;
}
}
System.out.println("数字个数："+digital);
System.out.println("英文字母个数："+character);
System.out.println("空格个数："+blank);
System.out.println("其他字符个数："+other);
}
}

Answer 1

修改后的代码：

import java.util.*;
public class test07 {
    public static void main(String[] args) {
        int digital=0;
        int character=0;
        int other=0;
        int blank=0;
        char[] ch=null;
        Scanner sc = new Scanner(System.in);	//修改一下
        String s =sc.nextLine();
        ch=s.toCharArray();
        for(int i=0; i<ch.length; i++) {
			//下面的ch改为ch[i]
            if(ch[i] >= '0'&&ch[i] <= '9') {
                digital++;
            } else if((ch[i] >= 'a'&&ch[i] <= 'z')||ch[i] >= 'A'&&ch[i] <= 'Z') {
                character++;
            } else if(ch[i] == ' ') {
                blank++;
            } else {
                other++;
            }
        }
        System.out.println("数字个数："+digital);
        System.out.println("英文字母个数："+character);
        System.out.println("空格个数："+blank);
        System.out.println("其他字符个数："+other);
    }
}

Answer 2

所有 >= 和 <= 前的ch改为ch[i]

Answer 3

查找的是ch【i】，不是整个ch数组