identifier.cpp

数据结构编程---串的知识

//【例3.1】  判断标识符。

#include "SString.h"                             //字符串类

bool isIdentifier(SString &str)                  //判断指定串是否为标识符
{
    if (str.length()>0)                          //有效字符串
    {
        char ch = str.charAt(0);                 //首字符
        if (ch>='A' && ch<='Z' || ch>='a' && ch<='z' || ch=='_' || ch=='$')  //字母开头
        {
            for (int i=1; i<str.length(); i++)
            {
                ch = str.charAt(i);
                if (!(ch>='A' && ch<='Z' || ch>='a' && ch<='z' || ch=='_' || ch=='$' || ch>='0' && ch<='9'))
                    return false;
            }
            return true;
        }
    }
    return false;
}

int main() 
{
    SString str("$_name1");
    cout<<str<<" isIdentifier? "<<isIdentifier(str)<<endl;
    return 0;
}
/*
程序运行结果如下：
"$_name1" isIdentifier? 1
"_name1" isIdentifier? 1

"1name" isIdentifier? 0
"name1+" isIdentifier? 0

"" isIdentifier? 0

*/