编译原理简单词法分析

/*编译原理简单词法分析 @关键字识别 @标识符判断 @常数（包括小数的识别(暂不支持负数)） @界符的识别 &将源文件扫描一遍& &将所有编码结果输出到编码文件当中& &常数和标识符分别单独再存到一个表中& &便于查找和识别& &避免二次写入&*/#include<stdio.h>#include<string.h>FILE *in,*out,*changshu,*biaozhifu;/*源文件编码文件常数表标识符表*/char key[][20]={"int","long","short","float","double","char","signed","undighed","static","const","void","if","else","do","while","switch","case","default","for","break","continue","goto","include","return","main"};int keynum=25;/*关键字的数量*/int NUMBER(char ch)/*数字*/{if(ch>='0'&&ch<='9')return 1;elsereturn 0;}int OPERATOR(char ch)/*运算符*/{if(ch=='+'||ch=='-'||ch=='*'||ch=='/'||ch=='='||ch=='^'||ch=='~'||ch=='&'||ch=='%'||ch=='<'||ch=='>'||ch=='.'||ch=='!')return 1;elsereturn 0;}int BOUNCE(char ch)/*界符*/{if(ch=='//'||ch==','||ch==';'||ch=='#'||ch=='{'||ch=='}'||ch=='('||ch==')'||ch=='"')return 1;elsereturn 0; }char buffer[50];/*定义一个缓冲区存放字符串*/int cflag=0;/*代表缓冲区中存放字符的个数*/int nflag=0;/*代表缓冲区存放数字的个数*/int nth=0;/*表示在常数表中存储的位置*/int bth=0;/*表示在标识符表中存储的位置*/int numflag=0;/*标志是否处于读书状态 1读数 0没读数*/char num[50];/*存放数字*/char Biaozhifu[100][20];/*存储已经定义的标识符*/char Changshu[100][100];/*存储已经出现过的常数*/void analysis(){int i;char ch;while(!feof(in)){ch=fgetc(in);if(NUMBER(ch))/*如果是数字*/{if(cflag)/*有可能在定义标识符避免遗漏 a1等情况*/{buffer[cflag++]=ch;}else{numflag=1;num[nflag++]=ch; }}else if(BOUNCE(ch))/*如果是界符*/{if(cflag)/*如果缓冲区中已存在字符*/{buffer[cflag]='/0';for(i=0;i<keynum;i++){if(strcmp(key[i],buffer)==0)break;}if(i<keynum){fprintf(out,"%s/t/t%d/t/t%s/n",buffer,3,"关键字");}else{for(i=0;i<bth;i++)/*判断此标识符是否在之前定义过*/{if(strcmp(Biaozhifu[i],buffer)==0)break;}if(i==bth){strcpy(Biaozhifu[bth],buffer);/*如果没有出现过 就将此标识符保存在Bianzhifu字符数组中 并写入标识符表中*/fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",buffer,1,"标识符",bth);fprintf(biaozhifu,"%s/t%d/n",buffer,bth++);}else/*如果已经出现过则*/{fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",buffer,1,"标识符",i);}}cflag=0;/*解除读字符状态*/}else if(numflag){num[nflag]='/0';for(i=0;i<nth;i++){if(strcmp(Changshu[i],num)==0)break;}if(i==nth)/*如果该数字在之前没有出现过 就将这个数字写入Changshu字符数组中 并相应写入常数表中*/{strcpy(Changshu[nth],num);fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",num,2,"常数",nth);fprintf(changshu,"%s/t%d/n",num,nth++);}else/*如果已经出现过*/{fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",num,2,"常数",i);}nflag=0;numflag=0;/*解除读数状态*/}fprintf(out,"%c/t/t%d/t/t%s/n",ch,5,"界符");}else if(OPERATOR(ch))/*如果是运算符*/{if(cflag)/*如果缓冲区中已存在字符*/{buffer[cflag]='/0';for(i=0;i<keynum;i++){if(strcmp(key[i],buffer)==0)break;}if(i<keynum){fprintf(out,"%s/t/t%d/t/t%s/n",buffer,3,"关键字");}else{for(i=0;i<bth;i++)/*判断此标识符是否在之前定义过*/{if(strcmp(Biaozhifu[i],buffer)==0)break;}if(i==bth){strcpy(Biaozhifu[bth],buffer);/*如果没有出现过 就将此标识符保存在Bianzhifu字符数组中 并写入标识符表中*/fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",buffer,1,"标识符",bth);fprintf(biaozhifu,"%s/t%d/n",buffer,bth++);}else/*如果已经出现过则*/{fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",buffer,1,"标识符",i);}}cflag=0;/*解除读字符状态*/}else if(numflag&&ch=='.'){num[nflag++]=ch;}if((ch=='.'&&!numflag)||ch!='.')//如果当前读入的为" ."并且之前没有数字则.为运算符{fprintf(out,"%c/t/t%d/t/t%s/n",ch,4,"运算符");}}else/*其它字符*/{if(ch==' '||ch=='/t'||ch=='/n'){if(cflag)/*如果缓冲区中已存在字符*/{buffer[cflag]='/0';for(i=0;i<keynum;i++){if(strcmp(key[i],buffer)==0)break;}if(i<keynum){fprintf(out,"%s/t/t%d/t/t%s/n",buffer,3,"关键字");}else{for(i=0;i<bth;i++)/*判断此标识符是否在之前定义过*/{if(strcmp(Biaozhifu[i],buffer)==0)break;}if(i==bth){strcpy(Biaozhifu[bth],buffer);/*如果没有出现过 就将此标识符保存在Bianzhifu字符数组中 并写入标识符表中*/fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",buffer,1,"标识符",bth);fprintf(biaozhifu,"%s/t%d/n",buffer,bth++);}else/*如果已经出现过则*/{fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",buffer,1,"标识符",i);}}cflag=0;/*解除读字符状态*/}else if(numflag){num[nflag]='/0';for(i=0;i<nth;i++){if(strcmp(Changshu[i],num)==0)break;}if(i==nth)/*如果该数字在之前没有出现过 就将这个数字写入Changshu字符数组中 并相应写入常数表中*/{strcpy(Changshu[nth],num);fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",num,2,"常数",nth);fprintf(changshu,"%s/t%d/n",num,nth++);}else/*如果已经出现过*/{fprintf(out,"%s/t/t%d/t/t%s/t/t%d/n",num,2,"常数",i);}numflag=0;/*解除读数状态*/nflag=0;}}else {if(ch=='e'&&numflag){num[nflag++]=ch;}elsebuffer[cflag++]=ch;}}}}void main(){in=fopen("源文件.c","r");out=fopen("编码文件.txt","w");changshu=fopen("常数.txt","w");biaozhifu=fopen("标识符.txt","w");fprintf(out,"%s/t/t%s/t%s /t%s/n","名称","属性标号","属性","对应表中序号");fprintf(biaozhifu,"%s/t%s/n","名称","序号");fprintf(changshu,"%s/t%s/n","名称","序号");analysis();fclose(in);fclose(out);fclose(changshu);fclose(biaozhifu);}/* @2011.4.15 @ Zhang Bing.*/