C :

#include<stdio.h>
#include<string.h>
main()
{
	char ch[10000];
	int i,num1,num2,num3,num4;
	while(gets(ch)!=NULL)
	{
		for(i=0,num1=0,num2=0,num3=0,num4=0;i<strlen(ch);i++)
		{
			if(ch[i]>='A'&&ch[i]<='Z'||ch[i]>='a'&&ch[i]<='z')
			num1++;//character
			else if(ch[i]==' ')
			num2++;//space
			else if(ch[i]>='0'&&ch[i]<='9')
			num3++;//number
			else
			num4++;//else
		}
		printf("%d %d %d %d\n",num1,num3,num2,num4);
	}
}

C++ :

#include<iostream>
#include<string>
#include<cctype>
using namespace std;
int main()
{
	string s;
	getline(cin,s);
	int letter=0,space=0,digit=0,other=0;
	int t=s.size();
	for (int i=0; i<t; i++)
		if (isalpha(s[i])) letter++;
		else if (isdigit(s[i])) digit++;
		else if (s[i]==' ') space++;
		else other++;
	cout<<letter<<" "<<digit<<" "<<space<<" "<<other<<endl;
	return 0;
}