学步园

#include <iostream><br /> #include <string><br /> using namespace std;</p> <p>int main()<br /> {<br /> string str("山丘之王");<br /> if(isdigit(str.at(0))||isalpha(str.at(0)))<br /> {<br /> cout << "对,就是这样" << endl;<br /> }<br /> system("pause");<br /> return 0;<br /> }

运行到if时,跳出错误:
Expression: (unsigned)(c+1) <=256

解决办法列出两种:
1.换成MBCS函数来做判断:
    if(_ismbcalnum(str.at(0))||_ismbcalpha(str.at(0)))
2.设置中文环境:
    setlocale( LC_CTYPE, "chs" );

#include <iostream><br /> #include <string><br /> #include <locale> //②<br /> #include <mbstring.h> //①<br /> using namespace std;</p> <p>int main()<br /> {<br /> setlocale( LC_CTYPE, "chs" ); //②</p> <p> string str("山丘之王");<br /> if(_ismbcalnum(str.at(0))||_ismbcalpha(str.at(0))) //①<br /> {<br /> cout << "对,就是这样" << endl;<br /> }<br /> system("pause");<br /> return 0;<br /> }