sh.c

用C语言编写的词法分析器

#include "stdio.h"
#include "string.h"
#include "ctype.h"
void analzid(FILE *output,char *p)
{
    int i=0;
    int count=0;
    if  (isalpha(p[0]))
{if    (strcmp(p,"if")==0)    {fprintf(output,"(3,if)\n");}
else if(strcmp(p,"then")==0)  {fprintf(output,"(4,then)\n");}
else if(strcmp(p,"else")==0)  {fprintf(output,"(5,else)\n");}
else if(strcmp(p,"while")==0) {fprintf(output,"(6,while)\n");}
else if(strcmp(p,"do")==0)    {fprintf(output,"(7,do)\n");}
else if(strcmp(p,"begin")==0) {fprintf(output,"(8,begin)\n");}
else if(strcmp(p,"end")==0)   {fprintf(output,"(9,end)\n");}
else if(strcmp(p,"long")==0)  {fprintf(output,"(10,long)\n");}
else if(strcmp(p,"switch")==0)   {fprintf(output,"(11,switch)\n");}
else if(strcmp(p,"case")==0)  {fprintf(output,"(12,case)\n");}
else if(strcmp(p,"enum")==0)  {fprintf(output,"(13,enum)\n");}
else if(strcmp(p,"register")==0) {fprintf(output,"(14,register)\n");}
else if(strcmp(p,"typedef")==0)  {fprintf(output,"(15,typedef)\n");}
else if(strcmp(p,"char")==0)     {fprintf(output,"(16,char)\n");}
else if(strcmp(p,"extern")==0) {fprintf(output,"(17,extern)\n");}
else if(strcmp(p,"return")==0) {fprintf(output,"(18,return)\n");}
else if(strcmp(p,"union")==0) {fprintf(output,"(19,union)\n");}
else if(strcmp(p,"const")==0) {fprintf(output,"(20,const)\n");}
else if(strcmp(p,"float")==0) {fprintf(output,"(21,float)\n");}
else if(strcmp(p,"short")==0) {fprintf(output,"(22,short)\n");}
else if(strcmp(p,"unsigned")==0) {fprintf(output,"(23,unsigned)\n");}
else if(strcmp(p,"continue")==0) {fprintf(output,"(24,continue)\n");}
else if(strcmp(p,"for")==0)   {fprintf(output,"(25,for)\n");}
else if(strcmp(p,"signed")==0) {fprintf(output,"(26,signed)\n");}
else if(strcmp(p,"void")==0) {fprintf(output,"(27,void)\n");}
else if(strcmp(p,"default")==0) {fprintf(output,"(28,default)\n");}
else if(strcmp(p,"goto")==0) {fprintf(output,"(29,goto)\n");}
else if(strcmp(p,"sizeof")==0) {fprintf(output,"(30,sizeof)\n");}
else if(strcmp(p,"volatile")==0) {fprintf(output,"(43,volatile)\n");}
else if(strcmp(p,"auto")==0) {fprintf(output,"(44,auto)\n");}
else if(strcmp(p,"double")==0) {fprintf(output,"(45,double)\n");}
else if(strcmp(p,"int")==0)   {fprintf(output,"(46,int)\n");}
else if(strcmp(p,"struct")==0) {fprintf(output,"(47,struct)\n");}
else if(strcmp(p,"break")==0) {fprintf(output,"(48,break)\n");}
else if(strcmp(p,"static")==0) {fprintf(output,"(49,static)\n");}
else {fprintf(output,"(1,%s)\n",p);}
    }
    else
    {for(;i<(int)strlen(p);i++) if(isdigit(p[i])) count++;
        if (count==(int)strlen(p))
        {fprintf(output,"(2,%s)\n",p);}
        else
        if (p[0]=='_'&&(isalpha(p[1])))
        {fprintf(output,"(1,%s)\n",p);}
        else {fprintf(output,"%s 未定义\n",p);}
    }
}
void analzsy(FILE *outfile,char *p)
{
    if     (strcmp(p,"=")==0)  {fprintf(outfile,"(37,=)\n");}
    else if(strcmp(p,"+")==0)  {fprintf(outfile,"(31,+)\n");}
    else if(strcmp(p,"-")==0)  {fprintf(outfile,"(32,-)\n");}
    else if(strcmp(p,"*")==0)  {fprintf(outfile,"(33,*)\n");}
    else if(strcmp(p,"/")==0)  {fprintf(outfile,"(34,/)\n");}
    else if(strcmp(p,"(")==0)  {fprintf(outfile,"(52,()\n");}
    else if(strcmp(p,")")==0)  {fprintf(outfile,"(53,))\n");}
    else if(strcmp(p,"[")==0)  {fprintf(outfile,"(55,[)\n");}
    else if(strcmp(p,"]")==0)  {fprintf(outfile,"(56,])\n");}
    else if(strcmp(p,"{")==0)  {fprintf(outfile,"(57,{)\n");}
    else if(strcmp(p,"}")==0)  {fprintf(outfile,"(58,})\n");}
    else if(strcmp(p,"<<")==0) {fprintf(outfile,"(59,<<)\n");}
    else if(strcmp(p,">>")==0) {fprintf(outfile,"(60,>>)\n");}
    else if(strcmp(p,"'")==0)  {fprintf(outfile,"(61,')\n");}
    else if(strcmp(p,"#")==0)  {fprintf(outfile,"(62,#)\n");}
    else if(strcmp(p,".")==0)  {fprintf(outfile,"(64,.)\n");}
    else if(strcmp(p,"*")==0)  {fprintf(outfile,"(33,*)\n");}
    else if(strcmp(p,"/")==0)  {fprintf(outfile,"(34,/)\n");}
    else if(strcmp(p,"%")==0)  {fprintf(outfile,"(40,%)\n");}
    else if(strcmp(p,",")==0)  {fprintf(outfile,"(64,,)\n");}
    else if(strcmp(p,":")==0)  {fprintf(outfile,"(65,:)\n");}
    else if(strcmp(p,";")==0)  {fprintf(outfile,"(54,;)\n");}
    else if(strcmp(p,">")==0)  {fprintf(outfile,"(36,>)\n");}
    else if(strcmp(p,"<")==0)  {fprintf(outfile,"(35,<)\n");}
    else if(strcmp(p,">=")==0) {fprintf(outfile,"(39,>=)\n");}
    else if(strcmp(p,"<=")==0) {fprintf(outfile,"(38,<=)\n");}
    else if(strcmp(p,"==")==0) {fprintf(outfile,"(41,==)\n");}
    else if(strcmp(p,"!=")==0) {fprintf(outfile,"(42,!=)\n");}
    else if(strcmp(p," ")==0)  ;
    else if(strcmp(p,"\n")==0) ;
    else {fprintf(outfile,"%s 未定义\n",p);}
}

void main()
{FILE *fp,*out;
int i=0,x=0,y=0;
int EA=0;
char ch,str[10000],idstr[10],systr[2];
if((fp=fopen("infile.txt","r"))==NULL)
    {printf("Can not open infile!\n");
        }
if((out=fopen("outfile.txt","w"))==NULL)
    {printf("Can not open outfile!\n");
       }
ch=fgetc(fp);

while(ch!=EOF)                //将infile.txt中的字符全部存入数组
{str[i]=ch;str[i+1]='\0';i++;ch=fgetc(fp);}
i=0;

while(1)
{
    if(str[i]=='@') break;   //遇到@则结束
    else 
        if((str[i]>='a'&&str[i]<='z')||(str[i]>='A'&&str[i]<='Z')||
           (str[i]>='0'&&str[i]<='9')||(str[i]=='_'))    //判断标识符
        {idstr[x]=str[i];idstr[x+1]='\0';x++;i++;EA=1;}
        else
        {
            x=0;
            if((strlen(idstr)!=0)&&(EA)) analzid(out,idstr);//将标识符输出到outfile.txt
            idstr[x]='\0';
            if(str[i]<'0'||(str[i]>'9'&&str[i]<'A')||
              (str[i]>'Z'&&str[i]<'a')||str[i]>'z')//判断除数字、字符之外的其他符号
            {
             if(str[i]!='!'&&str[i]!='='&&str[i]!='<'&&str[i]!='>')
             {
              systr[y]=str[i];systr[y+1]='\0';analzsy(out,systr);i++;
             }
             else 
             if((str[i]=='!'&&str[i+1]=='=')||(str[i]=='='&&str[i+1]=='=')||
                (str[i]=='>'&&str[i+1]=='=')||(str[i]=='<'&&str[i+1]=='=')||
                (str[i]=='<'&&str[i+1]=='<')||(str[i]=='>'&&str[i+1]=='>'))//判断双目符号
                {
                 systr[y]=str[i];systr[y+1]=str[i+1];systr[y+2]='\0';
                 analzsy(out,systr);i++;i++;//将双目符号输出
                }
                else
                {
                 systr[y]=str[i];systr[y+1]='\0';analzsy(out,systr);i++;
}}}}
printf("-----全部结果已经存入outfile.txt文档-----\n");
fprintf(out,"--------完成--------");
fclose(fp);
fclose(out);

}