输入一行字符，分别统计出其中英文字母、空格、数字和其他字符的个数

#include<iostream>
using namespace std;
int main(){
	char c;
	int s=0,z=0,k=0,q=0;
	while((c=getchar())!='\n'){
		int x=int(c);
		if(x>=48&&x<=57)s++;
		else if((x>=65&&x<=90)||(x>=97&&x<=122))z++;
		else if(x=32)k++;
		else q++;
	}
	cout<<"you have input "<<s<<" numbers"<<endl;
	cout<<"you have input "<<z<<" letters"<<endl;
	cout<<"you have input "<<k<<" spaces"<<endl;
	cout<<"you have input "<<q<<" some else chars"<<endl;
	return 0;
}

上面那个代码，是我知道字符对应的ASCII码所以才那样写的。当然也可以这样写：

#include<iostream>
using namespace std;
int main(){
	char c;
	int s=0,z=0,k=0,q=0;
	while((c=getchar())!='\n'){
		int x=int(c);
		if(x>='0'&&x<='9')s++;
		else if((x>='A'&&x<='Z')||(x>='a'&&x<='z'))z++;
		else if(x=' ')k++;
		else q++;
	}
	cout<<"you have input "<<s<<" numbers"<<endl;
	cout<<"you have input "<<z<<" letters"<<endl;
	cout<<"you have input "<<k<<" spaces"<<endl;
	cout<<"you have input "<<q<<" some else chars"<<endl;
	return 0;
}