C语言，输入一段字符，判断有几个大写字母，几个小写字母，几个数字，几个空格…
写这个程序，我们可以借用指针，判断了一个字符后，指针向右移动一个单位，判断下一个，以此类推，一直到此字符被判断完。
代码如下
#include<stdio.h>
#include<stdlib.h>
void check(char* n)
{
	int i = 0;
	int j = 0;
	int m = 0;
	int t = 0;
	int q = 0;
	while (*n != '\0')
	{
		if (*n >= 'a' && *n <= 'z')
		{
			i++;
		}
		else if (*n >= 'A' && *n <= 'Z')
		{
			j++;
		}
		else if (*n >= '0' && *n <= '9')
		{
			m++;
		}
		else if ((*n)==' ')
		{
			t++;
		}
		else
		{
			q++;
		}
		n++;
	}
	printf("小写字母%d个\n大写字母%d个\n数字%d个\n空格%d个\n其他%d个\n",i,j,m,t,q);
}

int main()
{
	char n[20] = { 0 };
	printf("请输入一段字符\n");
	gets(n);
	check(n);
	system("pause");
	return 0;
}

运行结果

在工作期间，将写内容过程经常用到的一些内容段做个记录，下面内容是关于Java判断一个字符是否是数字的几种方法的内容，希望能对码农们有好处。
public class Test
{
public static void main(String[] args)
{
char[] ch =
{
'a', '1', 'b', '2', 'c', '3', 'd', '4',
};
System.out.println(ch[0] + ": " + isDigitA(ch[0]));
System.out.println(ch[1] + ": " + isDigitA(ch[1]));
System.out.println(ch[2] + ": " + isDigitB(ch[2]));
System.out.println(ch[3] + ": " + isDigitB(ch[3]));
System.out.println(ch[4] + ": " + isDigitC(ch[4]));
System.out.println(ch[5] + ": " + isDigitC(ch[5]));
System.out.println(ch[6] + ": " + isDigitD(ch[6]));
System.out.println(ch[7] + ": " + isDigitD(ch[7]));
}
private static boolean isDigitA(char ch)
{
return Character.isDigit(ch);
}
private static boolean isDigitB(char ch)
{
Pattern pattern = Pattern.compile("[0-9]");
return pattern.matcher(String.valueOf(ch)).matches();
}
private static boolean isDigitC(char ch)
{
if (ch < 48 || ch > 57)
return false;
else
return true;
}
private static boolean isDigitD(char ch)
{
try
{
int i = Integer.parseInt(String.valueOf(ch));
return true;
}
catch (NumberFormatException e)
{
e.printStackTrace();
return false;
}
}
}

public static void main(String[] args) {
	
	int count_abc=0,count_num=0,count_oth=0;
	//输入一串数
	Scanner scan=new Scanner(System.in);
	String str = scan.next();
	char[] chars = str.toCharArray();
	//判断每个字符
	for(int i = 0;i<chars.length;i++){
		if((chars[i]>=65&&chars[i]<=90)||(chars[i]>=97&&chars[i]<=122)){
			count_abc++;
		}else if(chars[i]>=48&&chars[i]<=57){
			count_num++;
		}else{
			count_oth++;
		}
	}
	System.out.println("字母有："+count_abc+"个");
	System.out.println("数字有："+count_num+"个");
	System.out.println("其他的有："+count_oth+"个");
}




public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scan = new Scanner(System.in);
String getMess=scan.nextLine();
int zm=0;
int num=0;
int other=0;
char [] ch = getMess.toCharArray();
for(int i=0;i<ch.length;i++){
if((ch[i]>='a' && ch[i]<='z') || (ch[i]>='A' && ch[i]<='Z')){
zm=zm+1;
}else if(ch[i]>47 && ch[i]<58){
num=num+1;
}else{
other=other+1;
}
}
System.out.println("字母："+zm);
System.out.println("数字："+num);
System.out.println("其它："+other);
}

    
public static void main(String[] args) {

	int count_abc=0,count_num=0,count_oth=0;
	//输入一串数
	Scanner scan=new Scanner(System.in);
	String str = scan.next();
	char[] chars = str.toCharArray();
	//判断每个字符
	for(int i = 0;i<chars.length;i++){
		if((chars[i]>=65&&chars[i]<=90)||(chars[i]>=97&&chars[i]<=122)){
			count_abc++;
		}else if(chars[i]>=48&&chars[i]<=57){
			count_num++;
		}else{
			count_oth++;
		}
	}
	System.out.println("字母有："+count_abc+"个");
	System.out.println("数字有："+count_num+"个");
	System.out.println("其他的有："+count_oth+"个");
}

转载于:https://www.cnblogs.com/GodZhe/p/4777438.html