2424.txt

成绩数据库管理系统. 1．能够实现菜单显示、菜单选择、编辑（录入、插入、修改、删除等）、查找、显示、求总成绩、按总成绩排序（高→低）并显示、装入数据文件、数据文件存盘、退出、为数据动态分配存储空间[

[编译原理课程设计]程序示例一、词法分析器2007-06-21 12:31#include<string.h>
#include<stdio.h>
#define   MAX 22             /*分析表的最大容量*/
#define   RES_MAX   10        /*关键字的最大长度*/
#define   MAXBUF 255         /*缓冲区的大小*/
char   ch =' ';              /*存放读入当前的输入字符*/
int Line_NO;                /*纪录行号*/

struct reserve    /*关键字*/
{
char lexptr[MAXBUF];
int token;
};

struct reserve symtable[MAX];
char str[MAX][10]={"program","begin","end","var","integer","real", "for","if","then","else","do","while","array","procedure", "function","of","boolean","const","div","mod","and","or"};


void init()      /*对关键字表进行初始化，div,mod,and,or也作为关键字处理*/
{                /*最小的token是program：3，最大的token是or：24*/
int j;
for(j=0; j<MAX; j++)
{
   strcpy(symtable[j].lexptr,str[j]);
   symtable[j].token=j+3;   
}
}

/***************对关键字进行搜索**************/
int se_res(char * is_res){
   int i;
   for(i=0;i<MAX;i++){
     if((strcmp(symtable[i].lexptr,is_res))==0) break;
   }
   if(i<MAX) return   symtable[i].token;
   else return 0;
}

/*****************判断是否为字母*****************/
int IsLetter(char c)
{
    if(((c<='z')&&(c>='a'))||((c<='Z')&&(c>='A'))) return 1;
    else return 0;
}
/*************判断是否为数字**************/
int IsDigit(char c){
   if(c>='0'&c<='9') return 1;
   else return 0;
}

/***************分析程序**************/
void analyse(FILE *fpin,FILE *fpout){
    char arr[MAXBUF];       /* 输入缓冲区，存放一个单词符号 */
    int j=0;

    while((ch=fgetc(fpin))!=EOF){
    if(ch==' '||ch=='\t'){}                    /*碰到空格、tab则跳过*/
    else if(ch=='\n'){Line_NO++;}
/*************************字符串的处理****************************/
   else if(IsLetter(ch)){
       while(IsLetter(ch)|IsDigit(ch)){
            if((ch<='Z')&&(ch>='A'))     ch=ch+32;   /*忽略大小写*/
                  arr[j]=ch;
                  j++;
                  ch=fgetc(fpin);
        }
        fseek(fpin,-1L,SEEK_CUR);   /*输入指针回退一个字符*/
        arr[j]='\0';
        j=0;
       if (se_res(arr)){   /*如果是关键字*/
                 fprintf(fpout,"%s\t\t%d\n",arr,se_res(arr));
        }else   fprintf(fpout,"%s\t\t%d\n",arr,1);    /*普通标识符*/
/*************************数字的处理****************************/      
   }else if(IsDigit(ch)){
      while(IsDigit(ch)){
                         arr[j]=ch;
                         j++;
                         ch=fgetc(fpin);
        }
        fseek(fpin,-1L,SEEK_CUR);
        arr[j]='\0';
        j=0;
        fprintf(fpout,"%s\t\t%d\n",arr,2) ;     /*无符号整数*/
      }else switch(ch){           
               case'+' :fprintf(fpout,"%s\t\t%d\n","+",41);break;
               case'-' :fprintf(fpout,"%s\t\t%d\n","-",42);break;
               case'*' :fprintf(fpout,"%s\t\t%d\n","*",43);break;
               case'(' :fprintf(fpout,"%s\t\t%d\n","(",25);break;
               case')' :fprintf(fpout,"%s\t\t%d\n",")",26);break;
               case'[' :fprintf(fpout,"%s\t\t%d\n","[",27);break;
               case']' :fprintf(fpout,"%s\t\t%d\n","]",28);break;                      
               case';' :fprintf(fpout,"%s\t\t%d\n",";",36);break;
               case'=' :fprintf(fpout,"%s\t\t%d\n","=",38);break;
               case'.' :fprintf(fpout,"%s\t\t%d\n",".",39);break;
               case',' :fprintf(fpout,"%s\t\t%d\n",",",40);break;
                 
               case':' :{ch=fgetc(fpin);
         if(ch=='=') fprintf(fpout,"%s\t\t%d\n",":=",29);
               else {fprintf(fpout,"%s\t\t%d\n",":",30);fseek(fpin,-1L,SEEK_CUR);}
                 }break;

               case'>' :{ch=fgetc(fpin);
         if(ch=='=') fprintf(fpout,"%s\t\t%d\n",">=",30);
                         else {fprintf(fpout,"%s\t\t%d\n",">",31);fseek(fpin,-1L,SEEK_CUR);}
                         }break;

               case'<' :{ch=fgetc(fpin);
         if(ch=='=') fprintf(fpout,"%s\t\t%d\n","<=",34);
         else if(ch=='>') fprintf(fpout,"%s\t\t%d\n","<>",35);
                         else{fprintf(fpout,"%s\t\t%d\n","<",33);fseek(fpin,-1L,SEEK_CUR);}
                        }break;

   /***************出现在{ }之间的全部作为注释部分处理*******************/  
               case'{' :{ch=fgetc(fpin);
       while(ch!='}'&&ch!=EOF)   {ch=fgetc(fpin);}
         if(ch==EOF) fprintf(fpout,"缺少一个'}'");
                        }break; 
   /***************非法字符*******************/                         
               default :fprintf(fpout,"在第%d行无法识别的字符\t%c\n",Line_NO,ch);
        }
    }
}


/**********主程序中完成对输入输出文件的读写***********/
void main(){
   char in_fn[25],out_fn[25];
   FILE * fpin,* fpout;
   printf("//////////////chi fa fen xi qi////////////////\n");
   printf("input the input file exmaple:fin.txt:\n");
   scanf("%s",in_fn);
   printf("input the output file exmaple:fout.txt:\n");
   scanf("%s",out_fn);
   fpin=fopen(in_fn,"r");
   fpout=fopen(out_fn,"w");
   init();
   analyse(fpin,fpout);
   fclose(fpin);
   fclose(fpout);
}