第十二次作业

#include<string.h>
#include<stdio.h>
#include<stdlib.h>
void lrparser();
void yucu();
void scaner(); //词法分析
void statement();//语句
void condition();//条件
void expression();//表达式
void term();//项
void factor();//因子
int kk=0;
char prog[100],token[10];//输入程序段数组，大小为80
int syn,i=0,ks=0,js=0,m,n,sum=0,k=0;
char ch;
const char *blz[7]= {"begin","if","then","while","do","end","odd"};//保留字

int main() {
//    for(n=0;n<7;n++){
//        printf("%s",blz[n]);
//    }
    printf("********************语法分析程序***************\n");
    printf("请输入源程序,以#结束:\n");
    ch=getchar();
    while(ch!='#') {
        prog[i]=ch;
        ch=getchar();
        i++;
    }
    prog[i]='#';
    i++;
    prog[i]='\0';
    i=0;
    scaner();
    lrparser();
    printf("语法分析结束！\n");

}

void scaner() {
    printf("%c",ch);
    ch=prog[i++];
    while(ch == ' ' || ch == 10 || ch == 9||ch== 13) {//忽略空格换行回车和tab
        ch=prog[i++];
    }

    if((ch>='a' && ch<='z') ||(ch>='A' && ch<='Z')) {//判断是保留字还是标识符
        n=0;
        syn=10;//字母数字码为10
        char a=ch;
        while((ch>='a' && ch<='z') ||(ch>='A' && ch<='Z')||(ch>='0' && ch<='9')) {
            token[n++]=ch;
            ch=prog[i++];
        }
        token[n++]='\0';
        for(n=0; n<7; n++) {
            if(strcmp(token,blz[n])==0) {
                syn=n+1;//给保留字赋值，begin为1，if为2，then为3，while为4，do为5，end为6，odd为7
                printf("<%s,%d>\n",token,syn);
                if(syn==1) {
                    ks=1;
                }
                if(syn==6) {
                    js=6;
                }
                break;
            }
        }
        i--;
        if(syn==10) {
            ch=a;
            printf("<%c,%d>\n",ch,syn);
        }

    } else if(ch>='0' && ch<='9') {//数字判断
        syn=11;
        printf("<%c,%d>\n",ch,syn);
    } else {
        switch(ch) {//运算符，界符判断
            case '<':
                ch=prog[i++];
                if(ch=='>') {
                    syn=21;//当为<>时，数字码为21
                    printf("<%c,%d>\n",ch,syn);
                } else if(ch=='=') {
                    syn=22;//当为<=时，数字码为22
                    printf("<%c,%d>\n",ch,syn);
                } else {
                    i=i-1;
                    ch=token[i];
                    syn=20;//当为<时，数字码为20
                    printf("<%c,%d>\n",ch,syn);
                }
                break;
            case '>':
                ch=prog[i++];
                if(ch=='=') {
                    syn=24;//当为>=时，数字码为24
                    printf("<%c,%d>\n",ch,syn);
                } else {
                    i=i-1;
                    ch=prog[i];
                    syn=23;//当为>时，数字码为23
                    printf("<%c,%d>\n",ch,syn);
                }
                break;
            case ':':
                ch=prog[i++];
                if(ch=='=') {
                    syn=18;//当为:=时，数字码为18
                    printf("<%c,%d>\n",ch,syn);
                } else {
                    syn=17;//当为:时，数字码为17
                    i=i-1;
                    ch=prog[i];
                    printf("<%c,%d>\n",ch,syn);
                }
                break;
            case '+':
                syn=13;//当为+时，数字码为13
                printf("<%c,%d>\n",ch,syn);
                break;
            case '-'://当为-时，数字码为14
                syn=14;
                printf("<%c,%d>\n",ch,syn);
                break;
            case '*':
                syn=15;//当为*时，数字码为15
                printf("<%c,%d>\n",ch,syn);
                break;
            case '/':
                syn=16;//当为<>时，数字码为21
                printf("<%c,%d>\n",ch,syn);
                break;
            case ';':
                syn=26;//当为;时，数字码为26
                printf("<%c,%d>\n",ch,syn);
                break;
            case '(':
                syn=27;//当为(时，数字码为27
                printf("<%c,%d>\n",ch,syn);
                break;
            case ')'://当为)时，数字码为28
                syn=28;
                printf("<%c,%d>\n",ch,syn);
                break;
            case '='://当为=时，数字码为25
                syn=25;
                break;
            case '#'://当为#时，数字码为0
                syn=0;
                printf("<%c,%d>\n",ch,syn);
                break;
            default:
                syn=-1;
        }
    }
}
void lrparser() {
    if(ks==1) {
        scaner();
        yucu();
    } else {
        yucu();
        printf("语法错误缺失'begin'\n");
    }
    return;
}

void yucu() {
    statement();
    while(syn==26) {
        scaner();
        statement();
    }
    return;
}

void statement() {
    if (syn==10) { //为标识符
        scaner();
        if (syn==18||syn==25) { //为 :=
            scaner();
            expression();
        } else {
            printf("error!\n");
        }
    } else {
        if(syn==0&&ks==1&&js==6)
            printf("Success！语法无错误！分析完成\n");  //当匹配到#且begin、end存在时，输出语法无错误
        else if(syn==0&&js!=1) {
            printf("语法错误,缺失'end'\n");
        }
    }
    return;
}
void condition(){
    expression();
    if(syn==25||syn==20||syn==22||syn==23||syn==24)
    expression();
    while(syn==7){
        expression();
    }
    return;
}

void expression() {
    if(syn==13 || syn==14) {//为+或-时
        scaner();
        term();//处理项
    } else {
        term();
    }
    while(syn==13||syn==14) { //处理{(+|-)<项>}
        scaner();
        term();
    }
    return;
}

void term() {
    factor();
    while(syn==15 || syn==16) {//处理*|/时
        scaner();
        factor();
    }
    return;
}
void factor() {
    if(syn==10)
        scaner();
    else if(syn==11)
        scaner();
    else if(syn==27) {//左括号
        expression();
        if(syn==28)
            scaner();
        else {
            printf(" ')' 错误\n");
            kk=1;
        }
    }
    return;
}