C语言程序设计现代方法第二版的相关练习题

    #include <stdio.h>
    #include<string>
    
    int main(void)
    {
    	int ch;
    	printf("Enter phone number: ");
    
    	while ((ch = getchar()) != '\n') 
    	{
    		if (ch <= 'Z' && ch >= 'A')
    		{
    			switch (ch)
    			{
    			case 65: case 66: case 67:
    				printf("2");break;
    			case 68: case 69: case 70:
    				printf("3");break;
    			case 71: case 72: case 73:
    				printf("4");break;
    			case 74: case 75: case 76:
    				printf("5");break;
    			case 77: case 78: case 79:
    				printf("6");break;
    			case 81: case 82: case 83: case 80