山东省第二届ACM大学生程序设计竞赛:Identifiers

Identifiers

Time Limit: 1000ms Memory limit: 65536K 有疑问？点这里^_^

题目描述

Identifier is an important concept in the C programming language. Identifiers provide names for several language elements, such as functions, variables, labels, etc.

An identifier is a sequence of characters. A valid identifier can contain only upper and lower case alphabetic characters, underscore and digits, and must begin with an alphabetic character or an underscore. Given a list of chararcter sequences, write a program to check if they are valid identifiers.

输入

The first line of the input contains one integer, N, indicating the number of strings in the input. N lines follow, each of which contains at least one and no more than 100 characters. (only upper and lower case alphabetic characters, digits, underscore (" "), hyphen ("-"), period ("."), comma (","), colon (":"), semicolon (";"), exclamation mark ("!"), question mark ("?"), single and double quotation marks, parentheses, white space and square brackets may appear in the character sequences.)

输出

For each of the N lines, output "Yes" (without quote marks) if the character sequence contained in that line make a valid identifier; output "No" (without quote marks) otherwise.

示例输入

7ValidIdentifiervalid_identifiervalid_identifier0 invalid identifier1234567invalid identifieradefhklmruvwxyz12356790 -.,:;!?'"()[]ABCDGIJLMQRSTVWXYZ

示例输出

YesYesYesNoNoNoNo

提示

来源

山东省第二届ACM大学生程序设计竞赛

#include <iostream>#include <cstring>#include <string>#include <stdio.h>using namespace std;int judge1(char a){    if((a>=97&&a<=122)||(a>=65&&a<=90)||(a=='_'))        return 1;    return 0;}int judge2(char a){    if((a>=97&&a<=122)||(a>=65&&a<=90)||(a=='_')||(a>=48&&a<=57))        return 1;    return 0;}int main(){    int n;    cin>>n;    char b;    cin>>b;    while(n--)    {        char a[200];        gets(a);        if(judge1(a[0]))        {            int i=1,j=0;            while(a[i]!='\0')            {                if(judge2(a[i]))                {                    j++;                }                i++;            }            if(j==i-1)            {                cout<<"Yes"<<endl;            }            else                cout<<"No"<<endl;        }        else        {            cout<<"No"<<endl;        }    }    return 0;}