www.pudn.com > expression1124.rar > expression.cpp
#include
#include
#include
#define N 20
char filename[20]; //文件名
char ch[20];
struct expression //表达式结构
{
char c;
struct expression *next;
};
struct keyword //保留字表结构
{
char key[10]; //保留字
int num; //类别编码
}stu[13]={{"program",3},{"var",4},{"procedure",5},{"begin",6},{"end",7},{"if",8},
{"then",9},{"else",10},{"while",11},{"do",12},{"call",13},{"integer",14},{"real",15}},st;
struct symbol //运算符表结构
{
char s; //运算符
int num; //类别编码
}ope[5]={{'+',16},{'-',17},{'*',18},{'/',19},{'|',20}},op;
struct Id //标识符表结构
{
char str[20]; //标志符
}iden[N],ide;
struct number //常数表结构
{
int n; //常数
}num[N],nu;
struct word //单词结构
{
int type; //类别编码
char fword[20]; //单词
}dword[N],dword1;
struct expression *h1;
int a=0,b=0,c=0;
void creat1(); //存储保留字文件
void creat2(); //存储运算符文件
void creat3(); //存储标识符文件
void creat4(); //存储常数文件
void creat5(); //存储单词文件，即输出结果文件
void output1(); //显示保留字文件
void output2(); //显示运算符文件
void output3(); //显示标识符文件
void output4(); //显示常数文件
void output5(); //显示单词文件
//读取表达式文件显示并建立该结构链表
void init(struct expression *head)
{
FILE *fp;
char c;
struct expression *p1,*p2=head;
printf("请输入表达式的文件名:");
scanf("%s",filename);
if((fp=fopen(filename,"r"))==NULL)
{
printf("\nopen file error");
exit(1);
}
printf("表达式如下：\n");
c=getc(fp);
while(c!='#')
{
p1=(struct expression *)malloc(sizeof(struct expression)); //尾插法建链表
p1->c=c;
putchar(p1->c);
p2->next=p1;
p1->next=NULL;
p2=p1;
c=getc(fp);
}
p1=(struct expression *)malloc(sizeof(struct expression)); //链表尾添加'#'节点
p1->c='#';
p1->next=NULL;
p2->next=p1;
p2=p1;
fclose(fp);
}
//词法分析主过程
void chang()
{
struct expression *p=h1->next;
int i,j,m,n;
char data,sum,sh[10];
while(p->c!='#')
{
m=0;
if(p->c==' ') p=p->next;
if(p->c=='\n') p=p->next;
if((p->c>='a'&&p->c<='z')||(p->c>='A'&&p->c<='Z')) //处理标识符
{
ch[0]=p->c;
p=p->next;
i=1;
while((p->c>='a'&&p->c<='z')||(p->c>='A'&&p->c<='Z')||(p->c>='0'&&p->c<='9'))
{
ch[i]=p->c;
i++;
p=p->next;
}
ch[i]='\0'; //标识符存入ch
while(m<13)
{
if(strcmp(stu[m].key,ch)==0) //标识符与某保留字相同
{
strcpy(dword[a].fword,stu[m].key); //添加到单词表
dword[a].type=stu[m].num;
a++;
break;
}
else m++;
}
if(m>=13) //标识符与保留字不同
{
strcpy(iden[b].str,ch); //添加到标识符表
b++;
strcpy(dword[a].fword,ch); //添加到单词表
dword[a].type=1;
a++;
}
}
if(p->c>='0'&&p->c<='9') //处理常量
{
sh[0]=p->c;
j=1;
sum=data=p->c-48;
p=p->next;
while(p->c>='0'&&p->c<='9')
{
sh[j]=p->c;
j++;
data=p->c-48;
sum=sum*10+data; //数值转换
p=p->next;
}
sh[j]='\0';
strcpy(dword[a].fword,sh); //添加到单词表
dword[a].type=2;
a++;
num[c].n=sum; //添加到常量表
c++;
}
else
{
switch(p->c)
{
case '+':dword[a].fword[0]=ope[0].s; //添加到单词表
dword[a].type=ope[0].num;
a++;
p=p->next;
break;
case '-':dword[a].fword[0]=ope[1].s; //添加到单词表
dword[a].type=ope[1].num;
a++;
p=p->next;
break;
case '*':dword[a].fword[0]=ope[2].s; //添加到单词表
dword[a].type=ope[2].num;
a++;
p=p->next;
break;
case '/':dword[a].fword[0]=ope[3].s; //添加到单词表
dword[a].type=ope[3].num;
a++;
p=p->next;
break;
case '|':dword[a].fword[0]=ope[4].s; //添加到单词表
dword[a].type=ope[4].num;
a++;
p=p->next;
break;
default: if(p->c!='#') //出错处理
{
printf("\nError:%c",p->c);
p=p->next;
break;
}
else //表达式无误
{
creat1();
creat2();
creat3();
creat4();
creat5();
printf("\n1：显示各文件内容");
printf("\n2:退出");
scanf("%d",&n);
if(n==1)
{
output1();
output2();
output3();
output4();
output5();
}
}
}
}
}
}
//建立保留字文件
void creat1()
{
FILE *fp1;
printf("\n请输入存储保留字表的文件名:");
scanf("%s",filename);
fp1=fopen(filename,"w");
fwrite(stu,sizeof(struct keyword),13,fp1);
fclose(fp1);
}
//建立运算符文件
void creat2()
{
FILE *fp2;
printf("请输入存储运算符表的文件名:");
scanf("%s",filename);
fp2=fopen(filename,"w");
fwrite(ope,sizeof(struct symbol),5,fp2);
fclose(fp2);
}
//建立标识符文件
void creat3()
{
FILE *fp3;
printf("请输入存储标识符表的文件名:");
scanf("%s",filename);
fp3=fopen(filename,"w");
fwrite(iden,sizeof(struct Id),b,fp3);
fclose(fp3);
}
//建立常量文件
void creat4()
{
FILE *fp4;
printf("请输入存储常量表的文件名:");
scanf("%s",filename);
fp4=fopen(filename,"w");
fwrite(num,sizeof(struct number),c,fp4);
fclose(fp4);
}
//建立单词文件
void creat5()
{
FILE *fp5;
printf("请输入存储单词的文件名:");
scanf("%s",filename);
fp5=fopen(filename,"w");
fwrite(dword,sizeof(struct word),a,fp5);
fclose(fp5);
}
//读取保留字文件并显示
void output1()
{
FILE *fp1;
int i=0;
printf("\n请输入保留字表的文件名:");
scanf("%s",filename);
fp1=fopen(filename,"r");
while(i<13)
{
fread(&st,sizeof(struct keyword),1,fp1);
printf("<%s %d>\t",st.key,st.num);
i++;
}
fclose(fp1);
}
//读取运算符文件并显示
void output2()
{
FILE *fp2;
int i=0;
printf("\n请输入运算符表的文件名:");
scanf("%s",filename);
fp2=fopen(filename,"r");
while(i<5)
{
fread(&op,sizeof(struct symbol),1,fp2);
printf("<%c %d>\t",op.s,op.num);
i++;
}
fclose(fp2);
}
//读取标识符文件并显示
void output3()
{
FILE *fp3;
int i=0;
printf("\n请输入标识符表的文件名:");
scanf("%s",filename);
fp3=fopen(filename,"r");
while(i\t",dword1.fword,dword1.type);
i++;
}
fclose(fp5);
}
void main()
{
h1=(struct expression *)malloc(sizeof(struct expression));
h1->next=NULL;
init(h1);
chang();
}