練習6-2－Quality of life is not what you get but what you become

最後一位數字	修飾符號
1-3	-
4-7	(空白)
8-0	+

//---------------------------------------------------------------------------
/****************************************************************************
練習6-2：修改前一個程式，依分數的個位數印出+或-的符號。參考上表 *
****************************************************************************/
#include <iostream>
#include <string>
//---------------------------------------------------------------------------
std::string grades;
char last_char;
int n=1;

int main(int argc, char* argv[])
{
std::cout << "Enter grades,system will change last number to the "
<< "symbols as the upper form \n";

for (int i=1;i<=n;i){

std::cin >> grades;

j = grades.size()-1;
last_char = grades.at(j);

if ( last_char == '1' || last_char == '2' || last_char == '3')
std::cout << "-\n";

          else if ( last_char == '4' || last_char == '5' || last_char == '6'
               || last_char == '7')
            std::cout << " \n";

          else if ( last_char == '8' || last_char == '9' || last_char == '0')
            std::cout << "+\n";
        }
        std::system("pause");
        return 0;
}
//---------------------------------------------------------------------------

題目來源：C++風格與藝術第二版 Steve Oualline 著黃吉霈編譯
答案來源：自我撰寫(不保證正確喔)