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词法
#include iostream
#include fstream
#include string
#include ctype.h
#define NULL 0
using namespace std;
char str;
FILE *fp;
char *keyword[49]={"and","array","begin","end","case","const","div","do","downto","else","end","file","for","function",
"goto","if","in","label","mod","nil","of","packed","procedure","program","record","repeat","set","then","to","type",
"until","var","while","with","exports","shr","string","asm","object","unit","constructor","implementation",
"destructor","uses","inherited","inline","interface","library","shl"};
char *logicOperator[4]={"not","and","or","xor"};//逻辑运算符
char *comment[4]={"{","}","(*","*)"};//注释符
char *relation[6]={"=","","","","=","="};//关系运算符
char *separator[12]={"(",")","[","]",":=",",",";",".",":","..","'","^"};//界符
bool search(char str[],int wordtype)
{
int i;
switch (wordtype)
{
case 1:
for(i=0;i49;i++)
{if(strcmp(keyword,str)==0)
printf("%sn",keyword);
return true;}
break;
case 2:
for(i=0;i4;i++)
{if(strcmp(logicOperator,str)==0)return true;}
break;
case 3:
for(i=0;i4;i++)
{if(strcmp(comment,str)==0)return true;
}
break;
case 4:
for(i=0;i6;i++)
{if(strcmp(relation,str)==0)return true;
}
break;
case 5:
for(i=0;i12;i++)
{if(strcmp(separator,str)==0)return true;
}
break;
}
return (false);
}
int f(char c)
{
if((c='a'&&c='z')||(c='A')&&(c='Z'))
return 1;
else
return 0;
}
int digit(char c)
{
if((c='0'&&c='9')||c=='-'||c=='+'||c=='.')
return 1;
else
return 0;
}
char isLetter(char ch)
{
int i=-1;
char str1[20];
while(f(ch)||digit(ch))
{
str1[++i]=ch;
ch=fgetc(fp);
}
str1[i+1]=' ';
str=ch;
if (search(str1,1))
{printf("关键字,%sn",str1);
}
else if(search(str1,2))
{printf("逻辑运算符,%sn",str1);
}
else printf("标识符,%sn",str1);
return (ch);
}
void isDigit(char ch)
{
int i=-1,flag=-2;
char str1[20];
while (digit(ch)&&flag0)
{
if(ch=='.'){
flag++;
str1[++i]='.';
ch=fgetc(fp);
}
else
{
str1[++i]=ch;
ch=fgetc(fp);
}
}
str1[++i]=' ';
str=ch;
printf("数字,%sn",str1);
}
char isOther(char ch)
{
int i=-1;
char str1[5];
while(!digit(ch)&&!f(ch)&&ch!=' '&&ch!='n'&&ch!='t'&&ch!=EOF&&i=1)
{
str1[++i]=ch;
str1[i+1]=' ';
if (search(str1,3))
{printf("注释符,%sn",str1);
i=-1;
ch=fgetc(fp);
}
else if(search(str1,4))
{printf("关系运算符,%sn",str1);i=-1;
ch=fgetc(fp);
}
else if(search(str1,5))
{printf("界符,%sn",str1);i=-1;
ch=fgetc(fp);
}
else
ch=fgetc(fp);
}
if(i==2) printf("ERROR!n");
str=ch;
return ch;
}
int main()
{
if ((fp=fopen("sourcecode.txt","r"))==NULL)
{
cout"Open source file failed!"endl;
return 0;
}
str=fgetc(fp);
while(1)
{
if(str==EOF)break;
else if(str=='t'||str=='n'||str==' '){ str=fgetc(fp);;}
else if(isalpha(str)!=0)
{
str=isLetter(str);
}
else if(digit(str))
{
isDigit(str);
}
else
str=isOther(str);
}
fclose(fp);
return 0;
}
楼主 2015-12-24 11:13 回复
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