www.pudn.com > digui5.rar > digui5.cpp
/*
文法G(S)
S-->DGWE
G-->c=R
R-->dTe|d
T-->+|-|*|/
E-->aFb
F--> >|<
*/
#include
#include
#include
#include
char a[50],g[50][50]; //a[50]保存输入串,g[50][50]保存四元式
char ch;
int i1=0,i2=0,i3=0; //i1通过自加来取得a[i1]输入串中的字符 i2用来选择用哪种四元式,i3用来选择用'W'的报错
int total=0;
void S();
void D();
void G();
void W();
void E();
void R();
void T();
void F();
void main()
{
int p,j=0;
char str[20];
printf("请输入do-while语句(D代表do,W代表while),并以#结束:\n");
do{
scanf("%s",str);
if(strcmp(str,"do")==0)
{
a[j]='D';
j++;
}
else if(strcmp(str,"while")==0)
{
a[j]='W';
j++;
}
else if(strcmp(str,"c=d+e")==0)
{
a[j]='c';
a[j+1]='=';
a[j+2]='d';
a[j+3]='+';
a[j+4]='e';
j=j+5;
continue;
}
else if(strcmp(str,"c=d-e")==0)
{
a[j]='c';
a[j+1]='=';
a[j+2]='d';
a[j+3]='-';
a[j+4]='e';
j=j+5;
continue;
}
else if(strcmp(str,"c=d*e")==0)
{
a[j]='c';
a[j+1]='=';
a[j+2]='d';
a[j+3]='*';
a[j+4]='e';
j=j+5;
continue;
}
else if(strcmp(str,"c=d/e")==0)
{
a[j]='c';
a[j+1]='=';
a[j+2]='d';
a[j+3]='/';
a[j+4]='e';
j=j+5;
continue;
}
else if(strcmp(str,"a>b")==0)
{
a[j]='a';
a[j+1]='>';
a[j+2]='b';
j=j+3;
continue;
}
else if(strcmp(str,"aDGWE\n",total);total++;//total用来记数
D();
G();
}
void D()
{
if(ch!='D')
{ printf("第%d个字符%c为有非法字符请按回车返回!!",i1+1,ch);
getchar();
getchar();
exit(1);}
ch=a[++i1];
}
void G()
{ int i=i1+1;
if(ch!='c')
{ printf("第%d个字符%c为有非法字符请按回车返回!!",i1+1,ch);
getchar();
getchar();
exit(1);}
if(a[i]!='=')
{ printf("第%d个字符%c为有非法字符请按回车返回!!",i+1,a[i]);
getchar();
getchar();
exit(1);}
printf("%d\tG-->c=R\n",total);total++;
R();
}
void R()
{
int i;
i=i1+1;
i1=i1+2;
ch=a[i1];
if(a[i]!='=')
{
printf("第%d个字符%c为有非法字符请按回车返回!!",i+1,a[i]);
getchar();
getchar();
exit(1);
}
if(ch!='d')
{
printf("第%d个字符%c为有非法字符请按回车返回!!",i1+1,ch);
getchar();
getchar();
exit(1);
}
if((a[i1+1]=='+')||(a[i1+1]=='-')||(a[i1+1]=='*')||(a[i1+1]=='/'))
{
printf("%d\tR-->dTe\n",total);total++;
i2=3;
T();
}
else
{
printf("%d\tR-->d\n",total);total++;
i2=2;
strcpy(g[0],"(=,c,d,_)");
i3=1;
W();
E();
}
}
void T()
{
ch=a[++i1];
switch(ch)
{
case '+':
printf("%d\tT-->+\n",total);total++;
strcpy(g[0],"(+,d,e,T)");
strcpy(g[1],"(=,T,_,c)");
break;
case '-':
printf("%d\tT-->-\n",total);total++;
strcpy(g[0],"(-,d,e,T)");
strcpy(g[1],"(=,T,_,c)");
break;
case '*':
printf("%d\tT-->*\n",total);total++;
strcpy(g[0],"(*,d,e,T)");
strcpy(g[1],"(=,T,_,c)");
break;
default:
printf("%d\tT-->/\n",total);total++;
strcpy(g[0],"(/,d,e,T)");
strcpy(g[1],"(=,T,_,c)");
break;
}
W();
E();
}
void W()
{
if(i3==1)
{
ch=a[++i1];
if(ch!='W')
{
printf("第%d个字符%c为有非法字符请按回车返回!!",i1+1,ch);
getchar();
getchar();
exit(1);
}
}
else{++i1;
ch=a[++i1];
if(ch!='W')
{
printf("第%d个字符%c为有非法字符请按回车返回!!",i1+1,ch);
getchar();
getchar();
exit(1);
}
}
}
void E()
{
ch=a[++i1];
if(ch!='a')
{
printf("第%d个字符%c为有非法字符请按回车返回!!",i1+1,ch);
getchar();
getchar();
exit(1);
}
printf("%d\tE-->aFb\n",total);total++;
F();
}
void F()
{
int i;
ch=a[++i1];
i=i1+1;
if(a[i]!='b')
{
printf("第%d个字符%c为有非法字符请按回车返回!!",i+1,a[i]);
getchar();
getchar();
exit(1);
}
if(i2==2)
switch(ch)
{
case '>':
printf("%d\tF-->>\n",total);total++;
strcpy(g[1],"(j>,a,b,100)");
break;
default:
printf("%d\tF--> <\n",total);total++;
strcpy(g[1],"(j<,a,b,100)");
break;
}
else if(i2==3)
switch(ch)
{
case '>':
printf("%d\tF--> >\n",total);total++;
strcpy(g[2],"(j>,a,b,100)");
break;
default:
printf("%d\tF--> <\n",total);total++;
strcpy(g[2],"(j<,a,b,100)");
break;
}
ch='#';
}