1223递归

#include<stdio.h>
char curr;
char LL1[1000];
int N=-1;

void Top();
void Top1();
void Top2();
void top();
void top1();
void error();
void scaner();

void main()
{    char ch;
    int i=0;
    printf("请输入需要分析的curr语法:(以#结束)\n");
    do{
        scanf("%c",&ch);
        LL1[i] = ch;
        i++;
    }while(ch != '#');
    scaner();
    Top1();
    if(curr == '#')
        printf("成功!\n");
    else{
        printf("文法有误!!\n");
        error();
    }

}

void scaner(){   //用于读取源函数的下一个字符

    N++;
    if(LL1[N] == ' '){
        N++;
    }else{
        curr = LL1[N];
    }
}

void Top(){
    Top2();
    top();
}

void Top1(){
    Top();
    top1();
}

void Top2(){
    if(curr == '('){
        scaner();
        Top1();
        if(curr == ')'){
            scaner();
        }
		else
		{
            error();
		}
		else
		{
        //判断是否是函数或者是数字
        while(1){
            if(curr >= 'a' && curr<='z' || curr >= 'A' && curr <= 'Z' || curr >= '0' && curr <= '9'){
                scaner();
            }
			else
			{
                break;
            }
        }
    }
}

void top(){
    if(curr == '*'){
        scaner();
        Top2();
        Top();
    }else if(curr == '/'){
        scaner();
        Top2();
        Top();
    }else if(LL1[N+1] == '#' || LL1[N+1] == '+' || LL1[N+1] == '/' || LL1[N+1] == '*' || LL1[N+1] == '-'){
        if(LL1[N] != '(' && LL1[N] != ')')
        error();
    }
}

void top1(){
    if(curr == '+'){
        scaner();
        Top();
        top1();
    }
    else if(curr == '-'){
        scaner();
        Top();
        top1();
    }else if(LL1[N+1] == '#' || LL1[N+1] == '+' || LL1[N+1] == '/' || LL1[N+1] == '*' || LL1[N+1] == '-'){
        if(LL1[N] != '(' && LL1[N] != ')')
        error();
    }
}

void error(){
    printf("%d %c之后的文法有错!\n",N,curr);
}

  

posted @ 2015-12-23 17:50  53韩麒麟  阅读(139)  评论(0编辑  收藏  举报