3666 小C语言--词法分析程序

浅浅的花香味﹌ 2022-06-04 03:06 167阅读 0赞

[3666 小C语言–词法分析程序][3666 _C]

#include<stdio.h>
    #include<string.h>
    using namespace std;
    int isDigit(char ch)
    {
        if(ch >= '0'&& ch <= '9')
            return 1;
        else return 0;
    }
    int isCharacter(char ch)
    {
         if(ch >= 'a'&& ch <= 'z'||ch >= 'A'&& ch <= 'Z')
            return 1;
        else return 0;
    }
    int isOperator(char ch)
    {
        if(ch == '+'|| ch == '-'||ch == '*'|| ch == '/'||ch == '>'|| ch == '<'||ch == '!'|| ch == '=')
            return 1;
        else return 0;
    }
    int isKeyword(char tmp[])
    {
        if(!strcmp(tmp,"main")||!strcmp(tmp,"if")||!strcmp(tmp,"else")||!strcmp(tmp,"for")||!strcmp(tmp,"while")||!strcmp(tmp,"int"))
            return 1;
        else return 0;
    }
    int get()
    {
        char ch;
        char tmp[20];
        int i=0;
        while(~scanf("%c",&ch))
        {
            if(ch == '\t'||ch == ' ')
            continue;
            else if (isDigit(ch))
            {
                while(isDigit(ch))
                {
                tmp[i++] = ch;
                scanf("%c",&ch);
                }
                tmp[i] = '\0';
                i=0;
                printf("(integer,%s)\n",tmp);
                ungetc(ch,stdin);
            }
            else if(ch == '{'||ch == '}'||ch == '('||ch ==')'||ch == ','||ch ==';')
                printf("(boundary,%c)\n",ch);
            else if (isCharacter(ch)||ch == '_')
            {
                while(isCharacter(ch)||ch == '_'||isDigit(ch))
                {
                    tmp[i++] = ch;
                    scanf("%c",&ch);
                }
                tmp[i] = '\0';
                i=0;
                if(isKeyword(tmp))
                    printf("(keyword,%s)\n",tmp);
                else
                    printf("(identifier,%s)\n",tmp);
                ungetc(ch,stdin);
            }
            else if (isOperator(ch))
            {
                while(isOperator(ch))
                {
                    tmp[i++] = ch;
                    scanf("%c",&ch);
                }
                tmp[i] = '\0';
                i=0;
                printf("(operator,%s)\n",tmp);
                ungetc(ch,stdin);
            }
        }
    }
    int main()
    {
        get();
    }

[3666 _C]: http://acm.sdut.edu.cn/onlinejudge2/index.php/Home/Contest/contestproblem/cid/2246/pid/3666.html