//BY fertiland
#include<stdio.h>#include<ctype.h>#include<string.h>
void main(void);int reserver(char *);
void main(void){ FILE *input,*output; char ch,*token=""; int i=0,isReserver=0; int count=0; /*打开文件*/ if((input=fopen("input.txt","rt"))==NULL) { printf("file open in readonly mode,but an error generate!\n"); exit(0); } if((output=fopen("output.txt","wt"))==NULL) { printf("file open in new_create mode,but an error generate!\n"); exit(0); } fprintf(output,"%4s\t\%8s\t %-16s)\t%4s\n","位置","符号类型","识别符","长度"); ch=fgetc(input); while(ch!=EOF) { i=0; /*去掉前导空格,换行符*/ while((ch==' '||ch=='\n'||ch=='\t')&&ch!=EOF) ch=fgetc(input); /*字母开头*/ if(isalpha(ch)) { while(isalpha(ch)||isdigit(ch)) { token[i++]=ch; ch=fgetc(input); }
token[i]='\0'; isReserver=reserver(token); if(isReserver==1) {count++;fprintf(output,"%4d\t(标识符\t\t,%-16s)\t%4d\n",count,token,i);} else if(isReserver==0) {count++;fprintf(output,"%4d\t(保留字\t\t,%-16s)\t%4d\n",count,token,i);} else if(isReserver==2) {count++;fprintf(output,"%4d\t(算符\t\t,%-16s)\t%4d\n",count,token,i);} continue; } /*识别数字*/ else if(isdigit(ch)) { while(isdigit(ch)) { token[i++]=ch; ch=fgetc(input); } /*出现非数字且为点时*/ if (ch=='.') { token[i++]=ch; /*将点加入*/ ch=fgetc(input);/*读入下一个字符*/ if (isdigit(ch)) { while(isdigit(ch)) /*是数字时，收入，并将加一*/ { token[i++]=ch; ch=fgetc(input); } /*如果是数字加点再加数字再出现字母时，就是错误*/ if(isalpha(ch)) { while(isdigit(ch)||isalpha(ch)||ch=='.') { token[i++]=ch; ch=fgetc(input); } token[i]='\0'; count++;fprintf(output,"%4d\t(标识错误\t,%-16s)\t%4d\n",count,token,i); continue; } /*当出现结束符时，就收入为实数内*/ else { token[i]='\0'; count++;fprintf(output,"%4d\t(实数\t\t,%-16s)\t%4d\n",count,token,i); continue; } } } /*如果是字符,则判断为标识错误*/ else if(isalpha(ch)) { while(isdigit(ch)||isalpha(ch)||ch=='.') { token[i++]=ch; ch=fgetc(input); } token[i]='\0'; count++;fprintf(output,"%4d\t(标识错误\t,%-16s)\t%4d\n",token); continue; } /*如果是单词段结束符时，就判断为常数*/ else { token[i]='\0'; count++;fprintf(output,"%4d\t(常数\t\t,%-16s)\t%4d\n",count,token,i); continue; } } else if(ch=='(') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(右括号运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch==')') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(左括号运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='[') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(右中括号运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch==']') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(左中括号运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='-') { token[i++]=ch; ch=fgetc(input); if(ch=='-') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(自加运算符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } else if (ch=='>') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(指针运算符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } token[i]='\0'; count++;fprintf(output,"%4d\t(负运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='.') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(点运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='&') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(地址与运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='!') { token[i++]=ch; ch=fgetc(input); if(ch=='=') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(不等于比较符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } token[i]='\0'; count++;fprintf(output,"%4d\t(取反运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='~') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(按位运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='*') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(乘运算符\t,%-16s)\t%4d\t\n",count,token,i); continue; } else if(ch=='%') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(求余运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='/') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(除法运算符\t,%-16s)\t%4d\t\n",count,token,i); continue; } else if(ch=='<') { token[i++]=ch; ch=fgetc(input); if(ch=='=') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(小于等于比较符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } if(ch=='<') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(左移运算符\t,%-16s)\t%4d\t\n",count,token,i); ch=fgetc(input); continue; } token[i]='\0'; count++;fprintf(output,"%4d\t(小于比较符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='>') { token[i++]=ch; ch=fgetc(input); if(ch=='=') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(大于等于比较符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } if(ch=='>') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(右移运算符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } token[i]='\0'; count++;fprintf(output,"%4d\t(大于比较符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='=') { token[i++]=ch; ch=fgetc(input); if(ch=='=') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(等于比较符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } token[i]='\0'; count++;fprintf(output,"%4d\t(赋值运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch==',') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(逗号界符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch==';') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(分号界符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='{') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(边界运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='}') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(边界运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='+') { token[i++]=ch; ch=fgetc(input); if(ch=='+') { token[i++]=ch; token[i]='\0'; count++;fprintf(output,"%4d\t(自加运算符\t,%-16s)\t%4d\n",count,token,i); ch=fgetc(input); continue; } token[i]='\0'; count++;fprintf(output,"%4d\t(加运算符\t,%-16s)\t%4d\n",count,token,i); continue; } else if(ch=='"') { token[i++]=ch; ch=fgetc(input); while(ch!='"'&&ch!=EOF) { token[i++]=ch; ch=fgetc(input); } if(ch=='"') { token[i++]=ch; ch=fgetc(input); token[i]='\0'; count++;fprintf(output,"%4d\t(字符串\t\t,%-16s)\t%4d\n",count,token,i); continue; } else { while(ch!=EOF) { token[i++]=ch; ch=fgetc(input); } token[i]='\0'; count++;fprintf(output,"%4d\t(字符串错误\t,%-16s)\t%4d\n",count,token,i); } } else { while(ch!=' '&&ch!='\t'&&ch!='\n'&&ch!=EOF) { token[i++]=ch; ch=fgetc(input); } token[i]='\0'; count++;fprintf(output,"%4d\t(无法识别错误\t,%-16s)\t%4d\n",count,token,i); continue; } } fclose(input); fclose(output);}
/*判断是不是关键字: 1,则是标识符 0,则是关键字 2,则是运算符 */
int reserver(char *str){ FILE *fpReserver; char *tmpStr='\0';
if(strcmp(str,"sizeof")==0) return 2; /*打开关键字文件*/ if((fpReserver=fopen("keyword.txt","r"))==NULL) { printf("file open in readonly mode,but an error generate!\n"); exit(0); } while(fscanf(fpReserver,"%s",tmpStr)!=EOF) if(strcmp(str,tmpStr)==0) {fclose(fpReserver);return 0;} fclose(fpReserver); return 1; }
/*
输入文件input.txt
#include<stdio.h>
void E(char *);void E1(char *);void T(char *);void T1(char *);void F(char *);
void main(){ char *str="i+(i*i"; printf("%s\n",str); E(str);}
void E(char *str){ T(str); printf("1%s\n",str); E1(str); printf("2%s\n",str);}
void E1(char *str){ if (*str=='+') { str++; T(str); E1(str); }
}
void T(char *str){ F(str); T1(str);}void T1(char *str){ if(*str=='*') { str++; F(str); T1(str); }}
void F(char *str){ if(*str=='(') { str++; E(str); if(*str==')') str++; else { printf("lost ')'\n"); exit(0); } } else if(*str=='i') str++; else { printf("lost variable\n"); exit(0); }}
*/
/*
关键字文件keyword.txt
auto break case char constcontinue default do double elseenum extern float for gotoif int long register return short signed sizeof static structswitch typedef union unsigned voidvolatile while
*/
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[【技术文档】]c语言词法分析器