12 23 递归语法分析

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#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);
}

12 23 递归语法分析

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原文地址：http://www.cnblogs.com/wsstzxwx/p/5089259.html